Lightweight M1A build notes
Note: There's now FOUR pages of commentary. But a lot of it is just used for reference.
(04 Feb 2012) 7 lb 15 7/8 oz. w/handguard.
Another 22" barrel. Straight reamed F/H. Hopefully accuracy restored!
(14 Jan 2012)
For accuracy testing
(13 Jan 2012)
Freshly repaired old modified SEI pre-USCG brake
(07 Jan 2012)
LW rifle with first receiver modification to allow rearward placement of the ACOG:
LW rifle as of 3 Dec 2011:
7 lbs 13 1/4oz (but the scale seems to have added an 1 5/8oz to everything in this weight range...???)
Lightweight rifle as of 20 Nov 2011:
8 lbs 4 oz. with (modified) taller front sight base, lightened gas cylinder and plug, an art7 Mk.I lightened hammer, and of course, an adjustable AR stock.
Lightweight rifle as of 29 Oct 2011:
Subject to change!
Lightened the flash hider, gas cylinder, and gas plug since the photo above was done. The butt is being changed, too.
Note: Blog actually started here:
Pulled apart the "new" used rifle.
SAI, early "ban" probably. Empty weight right at 9 lbs, but with proper buttplate assembly, 9 lb. 6 oz.
1969 SAK barrel- will likely get pulled as it appears to be in good shape. Have an old SAI "NM" std weight barrel to replace it, but will shorten the replacement first.
TRW op rod- very good tab and cam. Tube OD is oddly rough. Will likely keep it.
HRT bolt. OK except extractor shows wear on top. Suspicious of that.
Lock bar rear sight adjuster, except missing clicker and tensioning spring. About useless. Will start by replacing with M14 adjuster. May do radical surgery in this area before it's all over.
Fiberglass stock and handguard. Black crinkle paint nastiness. Plus, Bubba decided to rotate the front swivel bracket about 80 degrees to the left. Rubber butt pad thingie.- all going away!
No bayonet lug, and front of flashhider slots severely gas eroded, even though the rifle itself appears low round count. Probably going away. But need an alternate front sight solution. Possibly variable height.
Trigger housing, fortunately, is a hideous cast commercial unit. Already made lightening cuts in the sidewall. A bit more aggressively than the first one done (that belongs to another rifle).
Previous example on top, current housing on bottom. (Note that the hammer is now an art7 Mk.I as of late November):
Current trigger housing weight- bare bones!: 3.4 oz.
Safety marked "K" over "8". New one on me.
Hammer is "HR-N" may try lightening it similar to the successful cast hammer mod shown below:
About 485gr. Standard hammer: 769gr.
Currently (as of 1-1-12) running an experimental Shooting Sight (art7's) http://www.shootingsight.com/ lightweight hammer, with a few mods of my own.:
Complete trigger groups now weigh 8.5 oz. (old) and 9.2 oz. (new). Hammer mod ought to get the new one lighter. Still a little extra meat in this area.
Found a front band that has unitizing holes drilled. Will see if i can get it welded up directly. Due to the nature of this build, the handguard ears won't be bent!
(04 Feb 2012) 7 lb 15 7/8 oz. w/handguard.
Another 22" barrel. Straight reamed F/H. Hopefully accuracy restored!
(14 Jan 2012)
For accuracy testing
(13 Jan 2012)
Freshly repaired old modified SEI pre-USCG brake
(07 Jan 2012)
LW rifle with first receiver modification to allow rearward placement of the ACOG:
LW rifle as of 3 Dec 2011:
7 lbs 13 1/4oz (but the scale seems to have added an 1 5/8oz to everything in this weight range...???)
Lightweight rifle as of 20 Nov 2011:
8 lbs 4 oz. with (modified) taller front sight base, lightened gas cylinder and plug, an art7 Mk.I lightened hammer, and of course, an adjustable AR stock.
Lightweight rifle as of 29 Oct 2011:
Subject to change!
Lightened the flash hider, gas cylinder, and gas plug since the photo above was done. The butt is being changed, too.
Note: Blog actually started here:
Pulled apart the "new" used rifle.
SAI, early "ban" probably. Empty weight right at 9 lbs, but with proper buttplate assembly, 9 lb. 6 oz.
1969 SAK barrel- will likely get pulled as it appears to be in good shape. Have an old SAI "NM" std weight barrel to replace it, but will shorten the replacement first.
TRW op rod- very good tab and cam. Tube OD is oddly rough. Will likely keep it.
HRT bolt. OK except extractor shows wear on top. Suspicious of that.
Lock bar rear sight adjuster, except missing clicker and tensioning spring. About useless. Will start by replacing with M14 adjuster. May do radical surgery in this area before it's all over.
Fiberglass stock and handguard. Black crinkle paint nastiness. Plus, Bubba decided to rotate the front swivel bracket about 80 degrees to the left. Rubber butt pad thingie.- all going away!
No bayonet lug, and front of flashhider slots severely gas eroded, even though the rifle itself appears low round count. Probably going away. But need an alternate front sight solution. Possibly variable height.
Trigger housing, fortunately, is a hideous cast commercial unit. Already made lightening cuts in the sidewall. A bit more aggressively than the first one done (that belongs to another rifle).
Previous example on top, current housing on bottom. (Note that the hammer is now an art7 Mk.I as of late November):
Current trigger housing weight- bare bones!: 3.4 oz.
Safety marked "K" over "8". New one on me.
Hammer is "HR-N" may try lightening it similar to the successful cast hammer mod shown below:
About 485gr. Standard hammer: 769gr.
Currently (as of 1-1-12) running an experimental Shooting Sight (art7's) http://www.shootingsight.com/ lightweight hammer, with a few mods of my own.:
Complete trigger groups now weigh 8.5 oz. (old) and 9.2 oz. (new). Hammer mod ought to get the new one lighter. Still a little extra meat in this area.
Found a front band that has unitizing holes drilled. Will see if i can get it welded up directly. Due to the nature of this build, the handguard ears won't be bent!
Total Comments 67
Comments
-
Swapped the SAK barrel for the ??? SAI "NM" std. weight.
SAK looks very good internally, and has a TE of about 1.
NM barrel gages 3 but it may be due to a longer throat. It also headspaces looser than the SAK, but it's no biggie.
The castle nut is severely off timed. Had to take a hammer and punch to it for removal. Same timing on the NM barrel.
Will probably face it off a bit, maybe 0.005".
Also had to peen the barrel shoulder to keep it from over rotating on installation. Probably a bum receiver, as the SAK barrel was peened also, probably by SAI, as it has their "Geneseo, Ill." marking. Works (removal took way more effort than anticipated!) and doesn't look too bad.
Initial tests will be done as a 22" barrel for baseline purposes. With and w/o flash hider, if i can scope the receiver with a spare mount. Otherwise, iron sights. Plan on cutting it back to 20 or 19" at least. 18.5" minimum.
Also, started whittling on the JAE stock last Saturday. More complex than first thought. Top and botton aren't parrallel. Ledges and pockets at all sorts of random depths.Posted September 13th, 2011 at 12:03 AM by jmoore
- Castle nut should require about 0.002-3" material removed for proper line up and tension, theoretically.
Installed ARMS18 mount on the receiver without fitment problems. Also M14 sight adjusting assembly, vs. the lock bar.
Gas block needs shimming. Lock nut poorly timed.Posted September 14th, 2011 at 12:06 AM by jmoore - Castle nut needed a bit more than the 0.003" that was machined off. Stoned the face and finally got it positioned w/o bending the spanner pliers.
Installed an M16 no trap buttstock and tube. Tube is VERY tight. Installed with C5-A copper anti-seize. Hopefully it'll come back off without drama.
Iron sights actually come up better than with the collapsing stock! Thinner covering, I guess. Not a bad look either.
Mounted an old 1" tubed SAI scope which is a bit odd. 3-9x with auto ballistic cam built in. Dot and crosshair.
Empty weight w/ black USGI handguard and scope: 9lb. 9 or 10oz. Which meets my goal of a scoped and iron sighted rifle weight under 10 lbs. Not even trying! But it needs refining: QD scope mount would be good.Posted September 15th, 2011 at 12:05 AM by jmoore
Updated September 15th, 2011 at 09:22 AM by jmoore (Speeling) - Test fire AOK, rifle-wise.
Scope seems to be a failure, which seems odd- I recall it working fine a few years back. Now the zero shifts when the power is changed. Too bad, but "good" and "variable power scope" have not historically gone together once the scope gets some "mileage" on it.
However, the accuracy (if not repeatability) is quite acceptible- almost TOO good! Might make me feel guilty cutting the barrel back.
Recoil was fairly noticable whilst wearing only a t-shirt.
Rear sight did jump a click or two and touch the scope bottom, but it had a black paster there just in case. Tightened the rear sight tensioning screw another click.
After a rough zero, the Prvi Partisan ball fired a five shot group of ~4 1/4". But the best three were in 1.040"! Considering the ahndheald bench technique, it's probable the outlying impacts were shooter induced.
Next up- 168gr FGMM. Impact some 4 1/2" higher- not unexpected with the lightweight barrel. First 5 rounds measure ~1.410" with the best four in 0.810".
Amazingly amazing! No name GI profile "NM" barrel, regular old neutered small bore GI flashhider, non-unitized gas cylinder/barrel band with an ill timed lock, and all on a lashed together rifle that was just purchased. Most excellent trigger housing lockup and plenty of fore end tension must be large contributing factors. Trigger pull is merely average.
Moved to a 200yd bench and ran some 168gr pills out there. Changed the power setting on the scope to 9x, which led to "bad" surprise number one. Round impact wasn't where it was expected! High right by ~4-5 inches. Group OK. Adjusted scope and had another go. Much better centered.
Changed power back to 3x- zero now way left. Bother.
At any rate, 200yd five shot groups were:
1) 3.250"
2) 3.5"
3) 3.080"
Retired the test rifle and shot a standing string with the McMillan stocked rifle just for giggles with the Prvi Partisan, but forgot to come up a few clicks for the light bullets for the first two shots fired. D'oh! Oh, well.
Photos coming.Posted September 15th, 2011 at 10:09 AM by jmoore
Updated September 15th, 2011 at 11:03 AM by jmoore - The McCann stock currently under test:
Old rifle, now returned to "retro":
New rifle, dedicated to these experiments:
Configuration 1:
Posted September 15th, 2011 at 01:27 PM by jmoore - Fancy benchrest gear for shooting at 200yds. Gen-u-wine Wally World bag for a hand cushion!:
Groups shot at 200yds (initial test):
Posted September 15th, 2011 at 01:28 PM by jmoore - Replaced ailing SAI 3-9x scope with Bausch and Lomb 24x scope for accuracy testing. Sits a little higher and further back.
Ordered an overpriced unitized gas block from Fulton Armory because of time constraints. Gotta pay for being in a hurry!
Held off getting a 18.5" barrel. Haven't decided whether to cut the current 22" bbl down, or try a new one. 18.5 seems on the short side, but 20" isn't very space saving. Need to find a short AND light muzzle attachment.Posted September 21st, 2011 at 12:59 AM by jmoore - Some links for easy reference:
McCann stock thread:
http://m14forum.com/modern-m14/94750...-me-out-3.html
JAE stock modification thread:
http://m14forum.com/modern-m14/10202...rror-show.html
Lightweight hammer thread:
http://m14forum.com/accuracy/103533-...ghtning-2.htmlPosted September 23rd, 2011 at 08:25 AM by jmoore - Meanwhile, back at the ranch, after three+ hours of removing metal and replacing cross screws with shorter ones, the JAE stock is down a whole 2.6 oz. (!) Lots of work to get results in aluminum.
Weight of the front end with the tensioner installed now at 1 lb. 10.2 oz. (No locking blocks)
Bottom of the fore end seems to be where most of the excess is, but it'll be tricky to remove w/o losing the interlocking keyways between the two halves.
Photos coming sometime.Posted September 23rd, 2011 at 08:38 AM by jmoore
Updated September 23rd, 2011 at 12:19 PM by jmoore - UPS showed up just as we were leaving for lunch. On board was a little package with some M14 goodies inside. A trigger guard to complete a spare trigger housing assembly, a rear sight "click" washer that is a little different than expected, and a new unitized gas cylinder (UCG) and shims.
The Fulton Armory UGC is welded top and bottom, which is a little different than others I've seen, but the welds look good and uniform, not too big and is freshly finished after welding. Better be good for $199!
BTW, If anybody is actually reading this mess, feel free to add to it! Hopefully these notes will help down the road.Posted September 23rd, 2011 at 12:18 PM by jmoore - Fulton Armory gas cylinder is OK except it was so tight and had such sharp edges at the rear of the splined ID that it pulled a small burr off the SAI no name "NM" barrel during installation. Removed the sharp edgeand tried it on a GI barrel- still fairly tight (light drive fit) but no burrs or any damage other than a burishing of the finish near the splines.
Gave the old cylinder and front band assembled on a barrel stub to a friend for unitizing, but SHOULD have kept the cylinder lock! The other two spares bind on the last thread of the SAI barrel. They work OK on the GI barrels tested.
Minor incompatibilities abound when mixing parts lately. Annoying.
May lighten the new gas cylinder some if it tests OK.
Also found a reamed flashhider with no lug. Probably will run that as well for a while, but it may be changed out for something shorter and lighter- Front sight is also in question.Posted September 26th, 2011 at 01:17 AM by jmoore - Retrieved gas cylinder lock AND chased the barrel threads a little with a thread file.
Added the thickest shim in the kit to the barrel assembly for a nice 4:30-5 o'clock gas cylinder lockscrew lockup. It did add some nose clearance to the front of the stock, so maybe I was a little premature in shortening it previously. Still OK, but noticable air behind the front band now. Roughly 0.040" gap.
Reamed F/H installed.
Current weight w/ M16 stock and ARMS #18 mount (no scope): 8 lb. 10 oz.
So, lighter end of a bare wood stock rifle weight range, but now w/ bottom rail AND scope mount. (Pistol grip, too, but it doesn't really add to shootability.)Posted September 27th, 2011 at 02:19 AM by jmoore
Updated November 4th, 2011 at 03:46 PM by jmoore ("I" befoe "E"...) - All that work and a fancy 24x scope and it may be marginally LESS accurate at 200yds. 1.5 to 2 MOA.
At 100 there were two 5 shot groups at 1" or under. But that don't mean squat at distance! Bench technique is "cobbled" at best. But still, it's a little discouraging. (In actual fact, the rifle shoots quite acceptably- but it won't satisfy the internet "deadshots".)
Wood blocks and carpet square front rest, leaky sandbag rear.
100yd FGMM
200yd FGMMPosted September 29th, 2011 at 02:33 PM by jmoore - Got it back and realized that the front band is welded on upside down!Quote:Originally Posted by jmoore
Gave the old cylinder and front band assembled on a barrel stub to a friend for unitizing...
Just damn!
Now to cut it loose and see what can be salvaged. Oh,well: it was worth what I paid...
Nothing much new to report otherwise.Posted October 13th, 2011 at 02:12 AM by jmoore - Might as well add photos of the install ugliness:Quote:Originally Posted by jmoore Fulton Armory gas cylinder is OK except it was so tight and had such sharp edges at the rear of the splined ID that it pulled a small burr off the SAI no name "NM" barrel during installation. Removed the sharp edgeand tried it on a GI barrel- still fairly tight (light drive fit) but no burrs or any damage other than a burishing of the finish near the splines.
Would have bothered me had this been a "real" barrel. But nothing seems to be harmed, and, as noted, no burr when tried on a GI barrel.Posted October 13th, 2011 at 02:21 AM by jmoore - Have since shot some more at 200yds- the rifle seems to be 1.5 MOA regardless of fore end support position or support hand placement. So whilst it's not incredibly accurate, it's not finicky, either. That seems a reasonable trade-off. Could spend more money on a new barrel, but for the purposes of this build, it seems distracting.
Did some salvage work on an old cut off and discarded Mini 14 aftermarket flashhider.
Now to test the effect on the rifle. The threads are quite snug, as the test barrel used was not the install barrel. Fortunately, the F/H is made of fairly soft steel, so the splines on the barrel above acted as a tap and peeled off a little metal off the F/H's threads. No damage to the barrel. (Unless the F/H is a little too snug!...)
If it works, the next step may be to shorten the barrel some. And probably lightening the F/H as well- plus a couple of wrenching flats. Reverse order is more likely!
In related developments, the alternate gas cylinder that's getting unitized is back at the weld "shop". (Hobby TIG- it's training for him, and minimal cost and effort for me.)Posted October 24th, 2011 at 05:44 AM by jmoore - The new flash hider doesn't seem to hurt accuracy overall at 200yds, but it surely required a huge vertical zero change! Guessing 18" high at 100 yards, but the impacts were off paper. Once that bit of ammo wastage was sorted, the scope was dialed "Up" 2 MOA and the 200yard teating commenced. The first group was the best yet out of this rifle, but the second was the worst shot to date with FGMM 168gr. However, the first low round sounded a bit "off", so...
The third was about normal. 30rds expended in all. (Or $30, depending on how you count!)
No real difference in felt recoil.
Oddly, the F/H did NOT shift, even though it's only held from rotating by a snug fit! Hmmm...
Find the brass! 28 or 29 in this photo. Not too scattered, fortunately.Posted October 27th, 2011 at 12:58 PM by jmoore - The recycled flash hider has no provision for a front sight, so as a quick remedy, a SEI gas cylinder lock sight base was pressed into service. I don't like losing the sight radius, due to presbyopia, but it's still a bit better than a AR rifle.
Couldn't leave things alone, as usual, so it got a lightening before installation as well. Could have gotten more extreme, but it's fairly small. Maybe later...
The timing of the lock is so different from the GI that all shims were removed to time things properly. Almost too early now, but reseating it seemed to help. ....So where DID that shim go???...errr.
Also added some wrenching flats to the F/H. Probably ought to turn down the useless bayonet adapter rings, but not before the next test firing.
Current set-up:
Posted October 29th, 2011 at 07:01 AM by jmoore - Couldn't leave all that excess mass (Oooh, ever so heavy...)
on the flash hider, so off it went:
Very windy (and fairly crowded) at the range, so dialed the scope back 2 MOA and checked zero at 100yds. No drama.
Removed the scope and tried the new iron sight set-up.
FNM surplus ball. 100yd zero required bottoming out the rear sight. Accuracy pretty good, but it was VERY uncomfortable due to the high comb. Need to raise the rear up at least 12-15 clicks to have any hope of good head positioning.
In actual fact, I wish the butt was much higher! Then it would be easy to justify completely new irons, probably in BUIS form. (Or FG42/Johnson M1944/StG57/Harvey Rifle style.)Posted November 4th, 2011 at 03:36 PM by jmoore -
Excellent work sir......... Love the trigger/trigger housing lighteningPosted November 4th, 2011 at 05:21 PM by JD Russell
