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Barrel shape, stiffness, harmonics and accuracy for the M14.

This is a discussion on Barrel shape, stiffness, harmonics and accuracy for the M14. within the Gus Fisher forums, part of the Gun Professionals category; Folks, many people don't know that it took us YEARS to get the M14 to shoot as good as the M1 Garand. We didn't equal ...


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Old December 24th, 2008, 08:43 PM   #1
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Barrel shape, stiffness, harmonics and accuracy for the M14.

Folks, many people don't know that it took us YEARS to get the M14 to shoot as good as the M1 Garand. We didn't equal the Garand until they came out with heavy barrels and then medium heavy barrels came out after that - at least in Marine use.

The standard M14 barrel is OK, but not well designed for optimum accuracy. It was designed for acceptable combat accuracy while taking weight off the rifle when carrying it with a 20 round mag full of ammo. The standard G.I. barrel goes up and down and up and down in barrel diameter before it gets to the gas cylinder. That is not good for stiffness or harmonics and thus negatively affects accuracy. Yes, I realize that the M14 with a standard barrel and in a rifle in good shape will still hit man sized targets at 500 yards quite well. But hunting can call for better than that even at mid ranges. The additional stiffness and smoother harmonics really makes a difference in practical accuracy.

One thing the Army Team did in the early years prior to coming up with the heavy barrel was to sleeve a standard barrel with I believe an aluminum sleeve. Ted Brown has talked about how much better these shot than the standard barrels. I'm sure they did. It improved stiffness and smoothed out the barrel harmonics. What they did was to sort of bring the barrel back to close to the standard contour of the M1 Garand. That was a very important reason the NM Garands shot so much better than standard contour NM M14 "light barrels," as we called them after the heavy barrels came out.

The medium heavy barrels on M14's are more like the contour of the Garand barrel, though they are a bit heavier at the breech. The added metal and more uniform shape makes them a much better shape than a standard barrel for accuracy at medium to long ranges.

OK, so what good is this information? Well, if about the maxium distance you will be shooting is one hundred to two hundred yards, a standard contour barrel is probably going to do you fine unless you are shooting in some kind of a match or hunting small game. For 300 and more yards and for a hunting rifle (even at shorter ranges), I would suggest a medium heavy barrel. There is not enough discernable difference between a Medium Heavy and a full Heavy barrel that I would ever consider it for a hunting rifle. Save the full heavy barrel for a tactical rifle or a NM rifle.

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Old December 24th, 2008, 09:22 PM   #2
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Good stuff as always Mr. Fisher. I hope you and yours have a very Merry Christmas.

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Old December 24th, 2008, 09:39 PM   #3
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Thanks for the great information. It's almost like getting an early Christmas gift.

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Old December 25th, 2008, 02:05 AM   #4
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Thanks for writing that Mr Fisher. Informative reading that helped me out.

Merry Christmas

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Old December 25th, 2008, 04:04 AM   #5
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Gus,

Is it practical to flute a take off heavy barrel? We pulled a heavy barrel off one of my M1As thinking it was the barrel that gave up, it turned out not so. The lug nuts were just shooting themselves loose. Lesson learned.. Now I have this barrel with less than 2K rounds through it that I want to build into my hunting rig. I like the full heavy contour through the guide, but I would like to have as much of that heavy full length fluted if I could. What would be the consequence by doing so, distorted bore??

Thanks and Merry Christmas!

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Old December 25th, 2008, 10:35 AM   #6
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Barrel weight, accuracy

Gus

Your synopsis of standard weight barrels "under most circumstances" is right on. Standard weight barrels are certainly more finicky when it comes to harmonics and stiffness, but this issue can normally be resolved by setting proper front band tension. I find it's easier to set proper front band tension without having to bed; with Armscorp receivers. The geometry of the receiver inherently creates the proper tension needed to anecdote the lack of stiffness in the barrel.

The downward draw flexes the steel and resist the forces of chaotic harmonics giving the bullet a more undisturbed plane to travel.

Where a great shooting standard weight barrel might hold a 2.5 inch group at 100 meters, a great medium weight barrel will hold a 1.5 inch group, over a 10 shot string at the same distance without the downward draw. However, if the standard barrel is set up properly and the two barrels are equal, they should shoot a more similar group.

The standard weight barrel is my barrel of choice for most purposes. As a multipurpose farm, ranch, battle or hunting rifle, the standard weight barrel is hard to beat.

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Old December 25th, 2008, 11:14 AM   #7
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I love it when people who know way more than me about the m14 talk about it in detail. Great info here. Thanks guys.

Mr. Fisher, while on the subject of barrels I was wondering what your opinion is of 18.5 inch "bush" or "scout" length barrels is? I've got a 18.5 inch medium weight Criterion barrel on my rifle and it seems to be putting up some good groups.

Thanks again for the info being exchanged here.

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Old December 27th, 2008, 01:01 AM   #8
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Quote:
Originally Posted by Bamban View Post
Gus,

Is it practical to flute a take off heavy barrel? We pulled a heavy barrel off one of my M1As thinking it was the barrel that gave up, it turned out not so. The lug nuts were just shooting themselves loose. Lesson learned.. Now I have this barrel with less than 2K rounds through it that I want to build into my hunting rig. I like the full heavy contour through the guide, but I would like to have as much of that heavy full length fluted if I could. What would be the consequence by doing so, distorted bore??

Thanks and Merry Christmas!
Well, never really thought about fluting a take off barrel. I have to say I don't have bunches of experience with fluted barrels. But, sure you could have it done and you should not loose accuracy as long as the machinist who did the work takes reasonable care.

And a Merry Christmas to you.

Thanks from budster
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Old December 27th, 2008, 01:14 AM   #9
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Quote:
Originally Posted by jywolfe View Post
Gus

Your synopsis of standard weight barrels "under most circumstances" is right on. Standard weight barrels are certainly more finicky when it comes to harmonics and stiffness, but this issue can normally be resolved by setting proper front band tension. I find it's easier to set proper front band tension without having to bed; with Armscorp receivers. The geometry of the receiver inherently creates the proper tension needed to anecdote the lack of stiffness in the barrel.

The downward draw flexes the steel and resist the forces of chaotic harmonics giving the bullet a more undisturbed plane to travel.

Where a great shooting standard weight barrel might hold a 2.5 inch group at 100 meters, a great medium weight barrel will hold a 1.5 inch group, over a 10 shot string at the same distance without the downward draw. However, if the standard barrel is set up properly and the two barrels are equal, they should shoot a more similar group.

The standard weight barrel is my barrel of choice for most purposes. As a multipurpose farm, ranch, battle or hunting rifle, the standard weight barrel is hard to beat.
Well, in our experience with G.I. NM standard configuration barrels - setting the front band position about every which way it could be done - would at the very best only result in a 1.5 to 2 minute of angle rifle at 300 yards. That's a 4.5 to 6 inch group. Yes, that's OK for a deer or larger game. However, those barrels had to have no more than .0003" variance in either the lands or the grooves throughout the bore. I'm not sure, but I doubt many standard configuration barrels will hold that tight of bore specs - unless you go with a Gene Barnett, Krieger or other NM quality "light" barrel. So I doubt a plain barrel will shoot that well.

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Old December 27th, 2008, 01:33 AM   #10
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Quote:
Originally Posted by Serpico1985 View Post
Mr. Fisher, while on the subject of barrels I was wondering what your opinion is of 18.5 inch "bush" or "scout" length barrels is? I've got a 18.5 inch medium weight Criterion barrel on my rifle and it seems to be putting up some good groups.
Are you ready for a very convaluted answer? Grin.

Almost all of my experience has been with full length barrels and the majority of that experience is in NM competition. So when I talk about accuracy most times, it means the kind that you can win with in NM competition. To do that, you have to have a rifle that will shoot right at or slightly under 1 MOA at 300 yards. (I try to separate my terminology by saying something like "hunting accuracy" when I don't mean NM accuracy.)

For deer or larger game, you have an 8 inch circle for the kill zone. So, even if your rifle will only shoot a 4 inch group at 100 yards, you still have a rifle that will keep the bullets in or very near that 8 inch circle at 200 yards.

Also, I may be prejudiced, but I don't see how taking 1 1/2" off the barrel of an M14 gives you any real advantage over the full 20" barrel as to ease of handling. The M14 is still a pretty long rifle even with the 18 1/2" barrel. The increase in muzzle blast and the lowering of velocity and accuracy potential - keeps me from ever wanting an M14 "carbine" like that.

You probably can get some good groups at 100 to even maybe 200 yards with the 18 1/2" barrel, though they won't be as good as a full length barrel at 200 yards - with the possibility of exceptions for unusual barrels.

So if you are getting accuracy that is good enough for what you want with the shorter barrel, then be happy.

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Old December 27th, 2008, 11:42 AM   #11
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Quote:
Originally Posted by Gus Fisher View Post
Well, in our experience with G.I. NM standard configuration barrels - setting the front band position about every which way it could be done - would at the very best only result in a 1.5 to 2 minute of angle rifle at 300 yards. That's a 4.5 to 6 inch group. Yes, that's OK for a deer or larger game. However, those barrels had to have no more than .0003" variance in either the lands or the grooves throughout the bore. I'm not sure, but I doubt many standard configuration barrels will hold that tight of bore specs - unless you go with a Gene Barnett, Krieger or other NM quality "light" barrel. So I doubt a plain barrel will shoot that well.
For clarification...

Those are 10 shot groups, correct?

Ammo- arsenal M118NM and/or "one size fits all" handloads from the loading room?

We as non-DOD folks also have the option of tuning up handloads that our particular rifle "likes..."

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Old December 27th, 2008, 12:15 PM   #12
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Barrel shape, stiffness, harmonics and accuracy for the M14.

I have a question that may strike many of you as absurd, but after reading the posts on this link for several days, it is obvious that most of you are really sharp, and are very knowledgeable guys.

Has there ever been a rifle design that uses the same principle for barrel stiffness that Dan Wesson revolvers employ; tensioning the barrel, pulling it out tightly? Besides giving extremely good accuracy (at least, in a handgun length barrel), this method of barrel attachment makes it extremely easy for the user/owner to change out barrels.

Don't laugh guys............seriously, does such a rifle exist?
Jim

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Old December 27th, 2008, 01:41 PM   #13
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Years ago there was a doodad on the market for AR's.. It had a sleeve and a nut, the sleeve would butt up against the front sight housing on an AR and the nut engaged the muzzle threads. By torquing the nut, you would put tension or "stretch" the front section of the barrel. By tuning the tension on the nut they claimed great accuracy improvements from a standard barrel.

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Old December 27th, 2008, 09:00 PM   #14
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Cool I Just Wonder...

Out of sheer curiousity, I wonder if anyone ever reproduced those aluminum stiffening sleeves? Get one finished in a 'flat parked' finish and put that over your barrel... Hey, if it worked in the '60's, it'd work now, wouldn't it?



Best!

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Old December 28th, 2008, 12:55 AM   #15
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Quote:
Originally Posted by 2336USMC View Post
For clarification...

Those are 10 shot groups, correct?

Ammo- arsenal M118NM and/or "one size fits all" handloads from the loading room?

We as non-DOD folks also have the option of tuning up handloads that our particular rifle "likes..."
You are correct those were 10 shot groups using NM ammo, one "standard" handload and what is now Federal's Gold Medal Match.

To be honest, I don't see where handloading is going to significantly increase the accuracy over Gold Medal Match.

Thanks from budster
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