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How long will an M14 stock stay tight with or without glass bedding?

This is a discussion on How long will an M14 stock stay tight with or without glass bedding? within the Gus Fisher forums, part of the Gun Professionals category; Part I This is a REALLY difficult thing to determine folks for many reasons. I will try to list as many reasons as I can ...


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Old April 19th, 2012, 11:30 AM   #1
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How long will an M14 stock stay tight with or without glass bedding?

Part I

This is a REALLY difficult thing to determine folks for many reasons. I will try to list as many reasons as I can think of in this post and explain other things that are pertinent to this discussion.

SPECIAL NOTE: One of the primary ways we figure out if a stock or bedding is too loose is by degradation of accuracy as the groups open up. The problem with this is there are so many other variables than a stock. Throat Erosion (TE) of the barrel really comes into play with a used barrel as the TE wears to the point it begin to degrades accuracy. The tightest stock or glass bedding job will NOT CURE a barrel that is wearing out or has worn out in the Throat. It is MUCH easier to track a stock getting loose when you START with a NEW barrel for that reason. When you have a barrel that is at the half way point or greater on Throat Erosion, it is tougher to figure out what part of the group sizes opening up is caused by the barrel and what is caused by loosening of the stock and/or something else. Now, if you are a handloader, you can place the bullet a little further out when the TE wears, but that is a topic all unto itself.

Another thing that will cause groups to open up with enough rounds fired is the wear on the Muzzle Crown. On NM rifles, we used to “touch up” the crown with a hand held crowning tool every 600 to 800 rounds fired to keep the absolute finest NM accuracy from the barrel. Now, VERY FEW civilians do that because they never HAD to do it with bolt action rifles. However, we fire more rounds out of an M14 in a one day shooting session than many be fired out of a bolt action hunting rifle in a year or more. You fire 20 rounds or less out of your bolt action hunting rifle and it will take YEARS before you see a stock get loose or a muzzle crown wear, or the rifle needing to be glass bedded or skim glassed, etc., etc. etc.

Also, you can have the finest NM barrel, glass bedded stock and ALL the NM modifications and the rifle will shot like crap when using CRAPOLA ammunition. While there is nothing wrong with buying whatever ammunition you can and no matter how cheap it is or where it came from, if you wish to do that - then you may as well stop reading right here. Your stock may and probably would still be plenty tight and you will never know it because the ammo is going to vary the accuracy so much as you change from brand to brand of ammunition.

1. Before we can even attempt to establish how long a stock should be expected to stay tight for accuracy, we had best establish exactly WHAT we expect “accuracy” to be and for what usage.

SO we have to establish a “Base Line” for ammunition. Since new M59, M80, or M118 7.62mm Ball is not readily available at your local gun shop in quantity and from a standard Lot of ammunition, perhaps the first thing we should do is SPECIFY what ammunition should be used when we talk about how long it will take for a rifle to loosen up. NM ammunition has a slower velocity than Ball Ammo, so it would take more rounds of it to loosen up a stock than Ball ammo as well. I propose the Base Line Ammunition should be either Federal’s American Eagle ammunition or Winchester’s QC 3130 Ball ammunition – whichever shoots BEST in YOUR rifle. This ammunition is as close as we can get to “Issue Ball Ammo” and will CONSISTANTLY give you two inch size, three to five shot groups (or smaller to much smaller groups) in as properly built STANDARD commercial M14 type rifle with G.I. issue size barrel at 100 yards, when shot by a competent shooter and from a bench rest. Either of these loads is the equivalent or even a little better than NEW issue 7.62mm ball ammunition was “back in the day” when M14’s were issued. The ammo and the bench rest take as much human error out of the equation on accuracy as we can usually expect.

2. OK now we have the Base Line Ammo, what is going to be our Base Line Accuracy to determine how long a stock will remain tight to give that kind of accuracy? A NM shooter or Sniper is going to require a much more accurate rifle than a standard Battle Rifle. Also, we ALL have our own individual ideas on what is “accurate enough” for our own, personal usage. Some folks don’t have a problem with a SOCCOM staying inside 4” at 100 yards, but for others (including me) that is clearly not acceptable. So perhaps the BEST way to go about this is whatever size groups your rifle shoots at 100 yards when all the parts are new or like new, how long will the stock keep it shooting like that?

Before we can really get into that, there are other things we must know and consider.

3. M14 receivers were held to Much, MUCH tighter tolerances in the bedding areas than any commercial receiver, though some commercial receivers are close. The reason for that was so they COULD make a bazillion receivers and stocks and the stocks would always be interchangeable with no fitting required. This was also an extremely important feature to replace broken, cracked or unserviceable stocks so easily. Commercial receivers are not held to NEARLY as tight of dimensions for the receiver bedding area, so a commercial receiver can be LOOSE in a NOS M14 rifle stock from day one. On the other hand with a commercial receiver, the stock and/or liner may be too TIGHT on a NOS M14 stock from day one. Very few people understand just how far commercial receivers STRAY from G.I. tolerances to fit G.I. stocks. No, just because a commercial receiver is CALLED an M1A or M14, it does not mean it will fit a G.I. stock.

4. One distinct advantage the wood M14 stock has over an M1 Garand stock is the metal stock liner with the M14 stock. It was put in there to reinforce the M14 stock so it was less likely to crack with that HUGE hole in it for the magazine well and to help ensure the stock would not crack as fast when firing rifle grenades. It ALSO acted something like an added bedding reinforcement and contained the twisting force of the receiver in recoil far better than a plain wood bedding surface. Because the receiver legs could not twist as much, the M14 stock does not shoot loose as fast as a plain wood Garand stock. If the legs of a Commercial receiver are not long enough front to back, the rifle will be loose from day one. For a while, SAinc. made their receiver legs at or even a little larger distance than G.I. receiver legs. Actually, that was great and especially for stocks with worn liners. However, that sometimes meant you had to FILE a G.I. stock liner to get the receiver legs to fit.

5. Even with that liner in place, we have to consider the type of wood used in M14 stocks. Birch was NEVER considered an acceptable alternative for walnut until walnut sources dried up and the wood got so expensive, BECAUSE Birch gets compressed faster by recoil and thus loosens up faster than walnut. If good walnut had not dried up and the price of the wood had not risen so high, it is almost a 100% certainty that there would never have been ANY birch stocks used on M14’s. Actually the metal stock liner in the M14 fitting the exacting tolerances of the M14 receiver legs so well, was what made birch work for military stocks.

6. This next point is REALLY difficult for many people to understand about G.I. Garand or M14 stocks when they have no background as a military Armorer. Garand and M14 stocks in service on active duty were allowed to get looser than what most gunsmiths and many civilians would accept. Normally on active duty, a wood stock would get cracked or broken before it loosened up enough to replace it. There was no criterion for replacing a loose wood stock in any of the Technical Manuals or Field Manuals except some really vague stuff about when the rifle does not target well. Considering the fact that the minimum accuracy standards for both the Garand and the M14 rifles were when NEW was something like 3 ½ to 4 ½ size group at 100 yards, a stock loose enough to cause accuracy problems was often not identified as quickly as civilians would do with their bolt action hunting rifles.

About the only time Garand or M14 stocks were replaced for looseness was when the Armorers got enough feedback that a certain rifle did not shoot well on the rifle range. IF the Armorer knew enough to check for a loose stock; he would put the loose stock on a rifle that was not issued, or put the loose stock on a worn out rifle that was going to be evac’d for replacement and swap the better stock off it, or may “find” or “introduce” a crack or break in the stock that would require replacement. What that means if the stock was so loose it would not hold a group AND there was nothing else that made it unserviceable and no other way to get it replaced, the Armorer would BREAK it so it would be replaced, though he had to do it carefully so he wouldn’t be caught. Squeezing the front end of the stock to get a crack there was the most common way to do it as it did not show signs of someone deliberately breaking the stock or breaking it through negligence. It just looked like the crack came naturally from enough firing. Oh and of course as a standard Infantry Weapons Repairman (Armorer) I never did anything like that…….. well, I knew enough and was careful enough not to get caught doing it. Grin.

If I have not yet bored you to tears, I could go on even more about what constituted accuracy with BATTLE rifles on active duty and the possible corrections, but I think I have hit that point enough.

7. If you are a NM shooter or if you don’t like to clean your rifles often, there is a good chance you are not going to take the barreled receiver out of the stock very often. When enough rounds are fired, oil and/or grease is GOING to be driven back under the receiver and on top of the bedding. That Oil/Grease on top of the stock will cause the receiver to Hydroplane something like car tires on a wet road. That plays ALL KINDS OF HECK with your group sizes. You may THINK you need a tighter stock or a skim glass job done, but quite often, all you have to do is get the Oil/Grease off the stock with a paper towel moistened with Acetone. You can have the tightest glass bedding job with the finest glass bedding material and if there is Oil/Grease on top of the bedding surfaces, the rifle will shoot weird flyers.

OK, I think I have covered many if not most of the reasons to explain why it is so difficult to discuss this topic and why you REALLY CAN’T have any hard and fast rules on when a stock is going to get loose enough to be noticed. We will continue the discussion in the next post.

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Old April 19th, 2012, 01:23 PM   #2
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Part II

Testing for looseness.

1. On THE Marine Corps Rifle Team, we Armorers tested the glass bedding for looseness by turning the rifle upside down on a bench and taking the Firing Mechanism out. Then we would slowly and carefully lift JUST the butt of the stock without touching the barrel. If the receiver dropped down even a little ways, we skim glassed it. Now, folks this test is WAY OVERBOARD for a stock on any other rifle than one used in that high of level of Competition. But when you have a Host of High Masters going against other High Masters for the National Individual or Team Matches, that is the sort of thing we had to do. Probably 70 percent or more of the standard Infantry Rifle Stocks on Active Duty would have failed that test in 1972 when I first stared working on M14’s, though.

OK, so what is a realistic test that will actually tell you when a stock is getting loose and causing a degradation of accuracy in your rifle?

2. I came up with this method to test M1 Garand stocks for looseness front to back, though it works just as well for M14 stocks. You check it by taking the firing mechanism out of the rifle and turning the rifle upside down on the bench. Then grab the barrel around the gas cylinder with your left hand and do not touch the stock with that hand. Grab the pistol grip of the stock with your right hand. Now with “push/pull” motions between your hands, you will feel if the receiver is loose fore and aft in the stock. If there is no discernible movement you can feel, stop there because that stock is most likely “Good to Go” for anything other than a NM or Sniper Rifle.

A. If you can just barely feel a tiny bit of movement, that is fine for an Infantry Rifle Stock, though it would be time to skim glass a NM rifle.

B. If you can feel between 1/32” and 1/16” of movement, that would still have been OK for a Standard Infantry Rifle Stock, though this is the point you need to think about glass bedding or a skim glass job. You also have to take into account if the rifle is beginning to throw weird flyers as this is most likely the cause of it.

C. Additionally, if you can feel just a bit of “side to side” movement, that would have been OK for a Standard Infantry Rifle, but really signals you need a glass job or skim glass. Again, look for weird flyers or the groups opening up.

D. If you can feel 1/16” or just slightly more movement, then I suggest replacing the stock or doing a glass job or skim glass. You are GOING to get weird flyers in your groups at this point.

E. When stocks get looser than that, it can and will cause FUNCTIONING problems in the rifles, especially if you have little tension on the trigger guard. What happens is the receiver is not held firmly so the Op Rod spring can not compress properly and feed the next round with surety. It is sort of like “limp wristing” when shooting a .45 Pistol. It actually LOOKS like the rifle is short stroking due to insufficient gas, but the loose stock is causing it.

3. ALONG with testing the receiver for looseness in the stock, we also have to consider the tension it takes to close the trigger guard (TG) because that is what locks the rifle together. You often have to address corrections for this before the stock loosens up front to back.

A. If there is virtually NO tension when the TG is closed, STOP and do not shoot the rifle. I can almost guarantee with 100 percent certainty that the TG is going to pop loose during firing. If you keep trying to close the trigger guard and shoot it, you can get really frustrated and that is when really bad accidents occur. This can be fixed temporarily by using shims made of thin strips of leather, folded up tag board, soda cans, etc. Though a permanent fix would be gluing thin strips of wood t the stock or better still, glass bedding the trigger housing.

B. If there is only a small amount of tension and if there is enough looseness in the stock front to rear, then it will cause weird flyers in your group.

C. If there is good tension, this actually helps keep the stock from wearing loose as fast for the receiver.

D. The greatest amount of tension is used by NM Armorers and almost no G.I. stock was ever fitted that tight, though there is no reason you should not have the kind of tension on even a standard wood stock. When I fit Garand stocks that are left long up and down and you have to file the stock to get correct trigger guard tension, I use the most worn TG I can find and file the stock only to where the TG tension will close like a NM stock. As the stock loosens up with enough rounds fired, then I replace the TG with one that has less wear on the TG lugs and that tightens things back up. You really can’t do this with a G.I. M14 stock, though perhaps some commercial stocks are made a little taller top to bottom and you could try something like that if you had a really worn TG.

Now, there will always be an exception to every rule in the real world. One time a customer had me rebarrel his Garand with a Criterion barrel BUT he did not have long before he was moving out of state. His stock had more than 1/16” movement and not much TG tension. I would have BET that rifle would not have held a good group ahead of time, but I function fired it after the barrel install to ensure it would function properly. I don’t know what kind of Angels that customer had on his side, but that STANDARD barrel in a LOOSE stock functioned perfectly and shot like a NM rifle. I was stunned. I did tell him he would have to get a replacement stock or a bedding job as that was not going to last long, though.

OK, getting kind of tired, so will add more in Part III later.

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Old April 20th, 2012, 10:13 AM   #3
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Part III.

In this part I’ll discuss what stock materials caused the stock to loosen up the fastest.

The number One (1.) on the list is what loosens up the fastest. As you go down the list, the stocks loosened up slower with each material used. This is taken from years of experience with all of them.

Stocks made from Standard materials and NOT glass bedded:
1. Chinese Chu Wood. Stocks
2. G.I. Birch stocks (Loosens up much faster than walnut)
3. G.I. Walnut stocks
4. G.I.. Fiberglass stocks.

Note 1.: Epoxy impregnating Stock Types 1. through 3. would make them last much longer, but is economically unsound.

Note 2: Most of the laminate stocks I've seen were too loose and had to be at least skim glassed so the action would fit good and tight. IF they make a laminate as tight as a G.I. stock, then the Laminate would become number 4.above and the Fiberglass stock would move to number 5.

Stocks that had been glass bedded:

5. G.I. Birch stocks
6. G.I. Walnut stocks
7. Heavy Old Fashioned “Bishop Style” oversize NM stocks
8. Laminate stocks.
9. G.I.. Fiberglass stocks
10. McMillan Stocks

Glass Bedding Materials. Poorest first and get’s better as you go down the list:

1. Micro Bed. High Tech stuff when Marine Armorers were the FIRST to glass bed NM Garands in 1957, but out of date only a few years later.

2. Fenwall. Used in some Marine Corps NM rifles as late as early 1975, then dropped for good later that year. Thank God.

3. Brownell’s Accra Glass. The formula has been updated over the years, but I don’t care for how “loose and sloppy” it is when trying to pack glass for a bedding job. Actually works better as an epoxy to glue wood stocks when cracked or broken.

4. Brownell’s Accra Glass GEL. The GEL formula has good body and it won’t flow out of the stock like the standard formula, as you pack the glass in. To my knowledge, Marine Corps NM Armorers never used this stuff or if they did, it was only used very little for NM M14’s before my time in 1973. HOWEVER, I use this to bring worn out Garand stocks back up to better than new. This is actually tougher than any plain wood.

5. Bisonite. When we began using this in 1974, you still had to measure and mix powdered fiberglass, or steel in it. The current formula has it pre mixed. This is still a good fiberglass to use on NM rifles.

6. Marine Tex. After we began using this in for Marine Corps rifles in the early 80’s, we dropped Bisonite completely. We continued to use this for at least the base coat of fiberglass as late as 1997, when I retired, for M40A1 Sniper Rifles and NM M14’s.

7. Brownell’s Steel Bed. We did not use a lot of this on Marine Corps Rifles as we found it really did not seem to be better than Marine Tex for the higher price of Steel Bed. I do think it is just a bit tougher than Marine Tex, though most people may never realize it.

8. Devcon Steel or Titanium Mix. We began using this in the Mid 80’s, but found it was DARN hard to work with as it is so loose and sloppy it is VERY difficult to do a really good “Base Coat” fiberglass job. HOWEVER, it is probably the best stuff I know of to do a Skim Glass and it excels at that.


In the next post, I will try to give some information on how many rounds fired before a wood stock loosens up and when you should expect to need to Skim Glass to tighten up a Fiberglass job.

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Last edited by Gus Fisher; April 20th, 2012 at 02:01 PM.
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Old April 20th, 2012, 12:01 PM   #4
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If you wanted a standard weight stock to bed, is there a laminate stock available???
If not, what is the best alternative???

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Old April 20th, 2012, 12:57 PM   #5
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Quote:
Originally Posted by forsyth793 View Post
If you wanted a standard weight stock to bed, is there a laminate stock available???
If not, what is the best alternative???
I have not purchased a laminate stock for an M1A in probably four or five years. The laminate stocks I was familiar with for both the Garand and M1A are as chunky as the fat birch stocks. Of course, you can file and sand them down to a smaller contour.

However, be advised unless they changed things drastically, you almost HAVE to at least skim glass most laminates as they came from the factory rather loose, unless they came with the stock liner or made with the stock liner. I woulld suggest you check with Boyd's and Wenig's to see what they have in the way of laminates and if they would be acceptable to you.

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Old April 20th, 2012, 04:50 PM   #6
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A. Birch holds up best if you rout and relieve deep and build up the bedding compound pillar fashion.

B. I've gotten satisfying interim results with Art L's wipe-down using acetone, then slap on some spar varnish. It's less than a skim re-bed, but the rifle may not need it.

C. The royal PITA with the unlugged M14 clones between real re-beddings is those little dewberry trigger group feet astride the magazine well. With a GI or standard-cut stock you will eventually shoot the glass bedding down close to the liner, this even if you cut and filled pillars with hard-drying epoxy material. You just don't have enough wood surface to diffuse the compression like you do with the M1 rifle's floorplate design. Expect to have to refresh the bedding there when the trigger group opens easier than it used to. I've found that stuff that comes in a stick, you pull off equal parts blue and white, roll them together between you fingers, works pretty well for this. It works easy and dries hard. Acetone and nail-file the bedding surfaces of the stock, apply some paste wax or shoe polish on the inside of the trigger group's feet for release agent, apply the epoxy (doesn't take much), slap it all back together, go shoot a season.

D. To trim or not trim the metal stock liner when glass-bedding. It's individual preference depending on how well the receiver and trigger group locked up before glass-bedding. Metal against metal laterally behind the magazine well used to be a universal no-no. We may have been over-thinking it. Where it does get important is if the receiver's legs and stock liner are wedged against each other vertically. One or the other needs a little file work. Might as well make it enough to support a bedding compound fill. And you're going to bevel the receiver's legs anyway so it'll come out without galling your glass bedding.

Gus, you've nailed everything else and then some. The good news for shooters with standard wood stocks on their 14 clones who want to glass them is they can expect the usual improvements that come from tightening up the gun and they don't have to switch to a fat log to get there.

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Old April 20th, 2012, 10:01 PM   #7
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A. Birch holds up best if you rout and relieve deep and build up the bedding compound pillar fashion.

B. I've gotten satisfying interim results with Art L's wipe-down using acetone, then slap on some spar varnish. It's less than a skim re-bed, but the rifle may not need it.

C. The royal PITA with the unlugged M14 clones between real re-beddings is those little dewberry trigger group feet astride the magazine well. With a GI or standard-cut stock you will eventually shoot the glass bedding down close to the liner, this even if you cut and filled pillars with hard-drying epoxy material. You just don't have enough wood surface to diffuse the compression like you do with the M1 rifle's floorplate design. Expect to have to refresh the bedding there when the trigger group opens easier than it used to. I've found that stuff that comes in a stick, you pull off equal parts blue and white, roll them together between you fingers, works pretty well for this. It works easy and dries hard. Acetone and nail-file the bedding surfaces of the stock, apply some paste wax or shoe polish on the inside of the trigger group's feet for release agent, apply the epoxy (doesn't take much), slap it all back together, go shoot a season.

D. To trim or not trim the metal stock liner when glass-bedding. It's individual preference depending on how well the receiver and trigger group locked up before glass-bedding. Metal against metal laterally behind the magazine well used to be a universal no-no. We may have been over-thinking it. Where it does get important is if the receiver's legs and stock liner are wedged against each other vertically. One or the other needs a little file work. Might as well make it enough to support a bedding compound fill. And you're going to bevel the receiver's legs anyway so it'll come out without galling your glass bedding.

Gus, you've nailed everything else and then some. The good news for shooters with standard wood stocks on their 14 clones who want to glass them is they can expect the usual improvements that come from tightening up the gun and they don't have to switch to a fat log to get there.
A. From years of seeing G.I. birch stocks used in NM Division Match guns right alongside GI Walnut stocks AND considering how the stocks all had the same number of rounds fired, the Birch stocks were always noticeably looser than Walnut when they came back from Division Matches for the annual rebuild prior to the next year's matches. Considering we used the same techniques to glass bed both kinds of stocks, that REALLY pointed out to us how much faster Birch wears loose than walnut.

What I've found works best with Birch stocks is to route out so much of it under and to the side of the receiver bedding surfaces, the receiver is actually held by an epoxy inner stock with a thin veneer or Brich on the outside that is really nothing more than a covering over the inner fiberglass stock. I've only ever allowed a couple of people (outside other Marine NM Armorers) to watch as I route out wood on a birch stock. It scares the living Do Do out of most people. Now when that's done, then the wood of the stock is no longer a consideration, because it is the "inner epoxy stock" that does the work and takes the recoil. It takes more time and glass bedding material the FIRST time you bed the stock, but for all subsequent skim glasses, it is the same as skim glassing a Walnut stock.

Ah, SEA STORY TIME, grin. By the time I was transferred to become the Team Armorer for the Post and Station Team at Edson Range and NCOIC of the Armory in late 1988, I had LOATHED Birch stocks for many years due to the way they beat down. We were fortunate in the fact our Team had had enough funds to get McMillan stocks on each shooter's primary gun, but we had wood stocks on their back up guns. We did not have many birch stocks on those back up guns and I would have been very happy to replace them all with walnut stocks. However, that was not to be due to psychology.

Two of my shooters had hung onto their back up guns with birch stocks only because they liked the color of the birch so much better and they actually got more out of those rifles because of it, but they had to be skim glassed more often and according to Murphy's Law, that was often in the middle of a Match rather than practice. OK, so I'm dealing with people who prefer the look of birch over the fact that birch went down more often. I could NOT convince them to give up their "pretty birch stocks." AAAARRRRGGGGGGHHHHH!!!

Those were the first Marine Corps stocks I ever routed out so much wood from under the bedding surfaces. I was grinning and chuckling in a devilish manner as I was doing it and loving the fact of every bit of birch I could cut out. AFTER I filled all that open space back in with bedding material, their stocks only had to be skim glassed as often as any stock and not nearly as often as it had been. Now, I did not explain what I had done to my shooters, BUT they did finally notice they did not need the rirfles skim glassed as often. I let them think it was "Armorer's Magic" for a while as that was their term. However, when they began to think it was because the Birch in their stocks had finally reached their compression point and why they lasted as long at the walnut stocks before needing a skim glass, that's when I finally told them what I had done to set them straight. They FINALLY got it about Birch wood, but were happy their "pretty birch stocks" were finally performing like walnut stocks.

And that reminds me of another shorter Sea Story. Back in 1975 after I had been on THE Marine Corps Rifle Team as the junior Armorer for a while, a shooter who I had come to know at the Division Match on Hawaii, came up to the van while he was waiting to go on the line for practice. I cleaned his gas system and we chatted while I was doing it. He asked how I liked it on the BIG Team and I said I was learning one heck of a lot. Then he asked me how I felt about "shooters." Now, I knew him pretty well and we joked often, so I replied in jest, "Shooters are fine as long as you remember to change their diapers three times a day and give them a new rattle once a week." I did not really mean that of course and he knew I was kidding and we both cracked up over it. HOWEVER, what I did NOT realize was who else may within hearing distance.

No other than the Team Captain was getting a cup of coffee from the large urn set up right outside the Van. He did NOT think it was at all funny. Later on my Gunny told me the Team Captain had spoken to him about it and he said he would take care of it. When he told me, he was suppsed to chew me out, but realized I was probably just joking. When I explained, he grinned, but told me to make sure who was around before I joked like that again. Actually, when I told the Gunny what I had actually said, he could not help but to chuckle.

B. I'm sorry I am not following to what part of which post you are refering to.

C. Yes, compared to the front of the Garand trigger housing, you have no where near the bedding surface on the front of the M14 trigger housing and because of that, it can and will loosen a bit faster on standard wood stocks. However, when you cut the wood and install pillars of glass bedding from the bottom of the stock that go all the way up to join the bedding under and to the inside of the receiver legs, it makes an extremely solid and long lasting foundation with the more advanced bedding compounds we have now.

We do have to remember that it was never intended the front end tabs of the M14 trigger housing would tighten down against or even rest against the stock liner, but rather the wood surface below it. I imagine this was done because with wood stocks shrinking or swelling, they did not wnat the trigger housing to clamp down on the stock liner. That's just a guess on my part, though.

BTW, in the mid 80's, I was routing Garand stocks very deep to the inside of the front and rear receiver legs for NM Garand stocks. I decided to run pillars under both the front and rear receiver legs on each side of those stocks. I was rather pleased with myself that I had independently come up with doing it that way. Well, shortly after I had occasion to get inside a somewhat recent NM Garand by Don "Mac" McCoy and found out he had been doing it that way for about 5 years. I just grinned and decided if I had independently come up with the same thing the Master Garandsmith was doing, that was plenty good enough even if I had not been the first to come up with the idea.

D. I actually liked it when SAinc. made their receiver legs so long front to back that one HAD to file the stock liner down just to get the receiver legs to go down into a G.I. liner. That was great for the fit of a standard stock with stock liner, but it made things more expensive for SAinc to fit them to G.I. stocks, so they SHORTENED the length where more recently they are too LOOSE in a G.I. stock liner. Of course glass bedding to the sides of the receiver legs better withstand the twisting force of the receiver in recoil vs plai wood.

As to whether or not (and how much) to route the stock liner for enough room for glass bedding to be put ahead of and behind the receiver legs:

When G.I. stock liners ARE a very tight fit against the receiver legs front to back, that will last longer than a glass job around the receiver legs. However, when the liner gets battered down, then you have to pull the lner back out of the stock and forge it back to fit. This is extremely time consuming and difficult once you have glassed the rifle. We considered doing that, but since you have to skim glass occasionally, we decided to use glass bedding around the receiver legs as that held just as tight until the glass had to be skim glassed anyway. IOW, it saved a lot of labor in the initial build precess and how fast we could tune up or rebuild them.

What we DID find out was a very thin layer of glass bedding ahead of and especially behind the receiver legs would not last as long. So we routed the liners out rather extensively to get the greatest amount of glass bedding there as possible. Then when it is time to skim glass, skim glassing around the receiver legs is NOTHING compared to having to pull the liners out, rework them and reinstall them. It ALSO made it MUCH easier to tighten things back up at Match sites with only a simple skim glass.

Real engineers have explained the reason for this is due to the way dissimilar materials react when force is applied to them. A thicker "wrap" of bedding material around the receiver legs withstands more shock with these dissimilar metals taking the force of recoil. Again, the Engineers of Springfield ARSENAL realized this and that's why they made the stock liner so much thicker behind the rear receiver legs in real G.I. stocks and replaced that recoil shoulder with metal whereas the Garand stocks only had wood there. .

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Old April 21st, 2012, 10:55 AM   #8
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PART IV

1. I have been wracking my brain trying to come up with estimates of round count numbers before a stock loosens up. This is extremely difficult for the following reasons:

A. Armorers in the Marine Corps WERE required to keep “Round Count Cards” on M14’s as well as every small arm in their armory and we did that all the way up though the first years of the M16A1 as well. That would have been a GREAT source of information on how long all the parts on M14’s lasted, but I don’t believe that information was ever collected into a data base. The cards were kept in each Armory and were only taken out and sent along when a firearm was Evac’d for replacement. By the time computers came along, we had stopped using round counts for over a decade.

B. GI M14 stocks were almost ALWAYS replaced from damage in use before they wore out to the point they were no longer deemed tight enough for “acceptable” accuracy for Service Use.

C. The “acceptable” amount of degradation of Service Accuracy was never really qualitatively defined anyway.

D. So I really can’t give you a round count on REAL M14 receivers and when they loosened up in real G.I. stocks.

F. Since most commercial receivers VARY so widely in how tight or loose they fit in G.I. stocks to begin with, I really can’t give an estimate on how soon they will loosen up enough to require bedding or replacement of the stock. However, the tighter the stock fit is to begin with, the longer it will remain tight. The best I can do here is refer you back to Part II to check how tight the stock is on the commercial receiver.

G. I also have to point out that with my NM background; I have a tendency to be a lot more persnickety about looseness of stocks and accuracy than was ever required in regular Infantry Weapons. So I have a TENDENCY to estimate a LOWER number of rounds fired causing looseness that degrades accuracy, than other people. With the caliber of shooters we had on THE Marine Corps Rifle Team, they would notice accuracy changes before less accomplished shooters would notice an accuracy change. Also, NM Armorers tried to always “stay ahead of the game” and we may and probably did skim glass sooner than was absolutely necessary. As barrels, stocks and ammunition improved over the years; that sort of messed with estimates as well.

For example: After we used them enough, we found the gilt edge of accuracy for very high levels of National Competition for our barrels. Gene Barnett barrels made from Premium Douglas barrel blanks would just start to lose their gilt edge of accuracy around 4,500 to 5,000 rounds. Krieger barrels lasted till around 6,000 to get to that point. After those round counts, group sizes would open up a bit every 100 rounds or so until finally they hit the point it was like falling off a cliff and the groups jumped way up in size. So when we noticed the accuracy starting to fall off, we replaced the barrel.

2. I can give you some idea of how many rounds fired before glass bedded stocks needed a glass job and these counts DO NOT include a double lugged/double torque screw rifle. They are for a rifle without a rear lug as well and you get slightly more rounds out of a rear lugged bedded rifle than a rifle that does not have a rear lug.

3. On THE Marine Corps Rifle Team in 1975, we were using NM “light” barrels with no rear lugs. From May 20th until we went to the Nationals the first week or so in August, we fired 120 rounds a day, EVERY DAY except for the days we shot Matches and the single day off we got on July 4th. That is a very rough total count of around 6,500 to 7,000 or more rounds fired. Now, each shooter had two rifles each, so I have to cut that figure in half for each rifle to 3,250 to 3,500 rounds for each rifle.

That year ALSO happened to be the first year we used Bisonite and all rifles started out tight when we issued them to the shooters because we had previously glassed or skim glassed them. We also only used G.I. walnut stocks for most of our rifles, though we did have some of the huge Bishop Walnut oversize stocks.

With Bisonite, we found we only had to skim glass the rifle two or three times in a shooting season. So taking these VERY rough figures, that meant the bedding lasted AT LEAST around 1,000 to not quite 1,600 rounds and they may have lasted as long as 1,700 rounds before requiring a skim glass. That’s an extremely rough average of 1,350 rounds fired before needing a skim glass.

4. Accraglass Gel does not last this long as it doesn’t have aluminum or metal floc in the compound. A ROUGH guess is if you are going to shoot a rifle and expect the accuracy out of it that we did, you will get maybe 800 rounds out of it before you need a skim glass. Of course if you only expect SERVICE GRADE accuracy, it will last much longer than that.

5. When Marine Tex came along, we only ever had to skim glass a rifle TWICE during the shooting season, so that’s roughly an average of 1,600 to as many as 1,750 rounds before needing a skim glass for NM accuracy. Of course it lasts even longer for SERVICE GRADE accuracy. The modern Bisonite is probably somewhat close to Marine Tex, though not quite that good.

6. This is pure guesswork as I don’t have NEAR the experience watching rifles being shot with Brownell’s Steel Bed, but a wild guess on my part would be maybe 1,700 to maybe at most 1,900 rounds for NM accuracy before needing a skim glass. Again, it lasts longer for Service Grade accuracy.

7. Of course, what throws these numbers WAY OFF is when we change the stock from plain wood to laminates and/or fiberglass. Laminates will last longer and a G.I. fiberglass stock longer than that and a McMillan stock longer than that. Also, if the person is not a very good shot, they may not notice a change of accuracy for more rounds than that.

8. I also have to state the round counts I have guesstimated came from COMPLETE NM glass jobs and not more simple glass jobs. So if your rifle does not have a full NM glass job, it probably will shoot loose a bit sooner.

9. If I have not completely lost you at this point, let me just say again these are only rough estimates and you will probably find things different for each rifle you own. You need to watch the round count on your barrel and glass job to give you an idea when you may need a skim glass and you need to keep in mind the information in Part II on how to check for a loose stock.

I want to close with what I think is one of the best stories I have on how long a bedding job lasts. I was explaining these things to a customer at a gun show and when I strongly suggested a skim glass before EVERY competition shooting season with an M14, his buddy with him loudly “Harrumphed.” When I politely asked him what he meant, he said he had had his Rem 700 glass bedded 8 years earlier and it was still shooting tight groups. (At this point I wanted to beat my head against the wall, but instead I offered him these words.)

I asked him how many rounds per hunting season he actually fired in that rifle and he didn’t reply. So I suggested that MOST people did not shoot an entire box of ammo in a whole year of hunting, but if they did, that was 20 rounds per year. At that rate, he would need to come back in about 18 to 25 more years to have the rifle skim glassed. It didn’t quite sink in, but fortunately while it confused him, his buddy caught right on, though. Well, at least I got the point across to the person that mattered. Grin.

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Old April 21st, 2012, 05:36 PM   #9
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Another great post by GUS,
who really should be writing a book about the M14
[ apparently there is already some of that going on around here,
but Gus's book would have EXPERIENCE and CREDIBILITY. ]

PS: IS MUNIMULA THE FUTURE FOR THE M14??

Many other PRECISION stocks for other rifles [ bolt actions mostly ] use alloy bedding surfaces embedded into wood, foam, fiberglass, or?? JAE is already doing something similar for the M14, AND ADDING their very trick bolt down receiver tensioners, which replace the springy trigger guard with repeatable torque bolts ... just like a real serious ACCURISED bolt action rifle.
So why not more ALLOY bedding designs the M14??

And how about some BEDDING SURFACES wear reports from people with an ALLOY SAGE or TROY stock that has seen some documented high round count?

PPS: I looked at a NEW BOYDS heavy walnut M14 stock today. From what I could see, milling a rectangular cut out to take a BIG ALLOY bedding block is an opportunity just waiting to happen.

Maybe once we get some ALL ALLOY stocks sold, we can find some time to make up some of these smaller stand alone ALLOY bedding blocks. Steel bedding blocks have been tried before for the M14 [ Bridgeport and Tanks ] but these steel blocks are smaller and still require conventional and complicated glass bedding into the stock. And both of these designs still rely on conventional stock materials for the receiver bottom and the trigger housing surfaces to set into.

What I am talking about is a massive 1 1/2" x 1.720" X 7" alloy rectangular block, with ALL the bedding and seating surfaces CNC machined out of alloy. Bedding one big rectangular alloy block into either a solid wood stock, or laminating up a wood stock out of sections built around the block, both seem like an interesting new solution to M14 bedding.

Or maybe not??

Maybe adding ALLOY bedding surfaces to a "CLASSIC" M14 wood stock exterior is blasphemy rather than progress??

YPMMV
LAZ 1
[;)

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Old April 22nd, 2012, 09:12 AM   #10
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My experiences, though somewhat limited, with alloy blocks in fiberglass stocks for bolt action rifles has not been so hot. I've actually glass bedded some after roughing up the alloy blocks and covering them along with fiberglass to support the rest of the receiver.

I'm wondering one thing about an insert block, do you intend to have the trigger housing lock up o the bottom of it? That could be another PITA the way the "D" cuts for the triggerguard in so many commercial receivers were not made to spec. and vary so much up and down.

Thanks from Lazerus2000 and budster
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Old April 22nd, 2012, 09:54 AM   #11
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Gus, something I have been wondering. Were the same rifles used for bayonet practice as well as marksmanship/rangetime? I have to think that the former would have a bit of impact (no pun intended) on metal fit.

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Old April 22nd, 2012, 10:36 AM   #12
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once again Gus put his finger directly in it ....

Quote:
Originally Posted by Gus Fisher View Post
I'm wondering one thing about an insert block, do you intend to have the trigger housing lock up o the bottom of it? That could be another PITA the way the "D" cuts for the triggerguard in so many commercial receivers were not made to spec. and vary so much up and down.
The trigger housing bearing surfaces are indeed part of the lock up to the bedding block [ and the complete EBR stock as well ] .
And yes, getting these just right,
for proper bearing and draw tension,
has indeed been a PITA!!!


We have achieved a very good fit with several tested receivers and trigger guards, even while switching around the trigger assemblies between receivers. Fit is probably more consistent than most GI Glass stocks [ many of which are worn or twisted from age]. But we know that we can't make our alloy stock fit EVERY variation of receiver and trigger guard perfectly. This is one place where the old "cast in place" glass bedding materials will probably always have an advantage over mass produced alloy blocks.

PS: It looks like we will be making some more "Bedding fit test blocks" available for potential customers to try out before buying. This is one solution to the issues, but not necessarily the final solution.
[;)
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Old April 22nd, 2012, 03:58 PM   #13
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Quote:
Originally Posted by Depth Afield View Post
Gus, something I have been wondering. Were the same rifles used for bayonet practice as well as marksmanship/rangetime? I have to think that the former would have a bit of impact (no pun intended) on metal fit.
When I came around and we still had the M14 as the Battle Rifle of the 1st Marine Division, they/we did not do realistic fighting with rifles and sheathed bayonets. They/we always used Pugil Sticks for that training.

Thanks from budster
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Old April 22nd, 2012, 03:59 PM   #14
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Quote:
Originally Posted by Lazerus2000 View Post
The trigger housing bearing surfaces are indeed part of the lock up to the bedding block [ and the complete EBR stock as well ] .
And yes, getting these just right,
for proper bearing and draw tension,
has indeed been a PITA!!!


[;)
LAZ 1
I can only imagine the way D cuts vary so much in so many commercial receivers.

Thanks from budster
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Old February 26th, 2013, 09:47 AM   #15
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...I'm feeling like I've bought a can of worms here...

...reading between the lines it seems like you are carefully allowing that one might expect to get 1000 rounds out of a SA NM M1A before it shoots loose...???...

...thank you for taking the time to post this information...I believe I will be reffering to it freqently in the near future...

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