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Discussion Starter · #1 ·
I purchased a new Springfield SM, stainless Dougles barrel, walnut stock a couple of years ago. Its been several trips back to the factory, to a master gunsmith that specialized in M14 match rifles and another trip to the factory at this time. Here is what has happened:

Rifle shooting good, 0.5" group at 100 yds. About 40 rounds in the same hole, change to new target, 3 rounds in one hole, then 2.5" to 4" groups, whose center walked around forming a much larger group of about 7" consisting of 2.5" subgroups of about 7 rounds each.

OK sights lose or something broke. No, nothing found by many eyes and factory.

Rifle shoots .75" groups of 5 at 100 yards when single loaded.

With magazine, Rifle consistently shoots 3 rounds in one hole, 0.4" group or less and round 4 is about 1.8" round 5 is 2.5". Each new magazine causes new group center. see attachment photo.

No parts of the barrel touch anything, verified with pressure sensative paper.

Ammo makes little difference as long as its quality, eg GM Match, BH Match, LC Match, 150gr 168gr, 173gr, 175gr.

Iron sights or scope, same result.

Observations:

1 Rifle headspace is 1.631" factory, verified myself.

2. Fired brass headspace measure varies from 1.6305" to 1.6345" Order not recorded.

3. Some brass has horizontal scratch about 1/3 distance from open end. Depth varies from just perceptable to deep 0.020" or more. Source unknown at this time.

4. Factory inspection as well as mine and gunsmith does not show any damage to bedding or anything else.

5. Several magazines tried, no difference.

6. Crown is good, gas system solid, replaced anyway. Stock tension ok, op rod ok.

7. Barrel appears ok.

8. About 500 rounds, most test ammo, fired.

9. When 20 round group fired it is about 2.5" round at 100 yds.

Can anyone help? All suggestions welcome.

This is a competition rifle and needs to shoot less than 1 moa, preferably 1/2 moa or better. It did so for the first 43 or so rounds. plus one earlier competitiion, about 100 rounds.

Sincerely
Jack
 

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Welcome to the forum Jack.

I would be concerned that what ever is scratching your brass may be scratching the bullet when it's auto loaded from a mag.

Have you ejected a live round to see if the bullet has been damaged?

Seems like there was thread about this a few years ago. I'm just thinking out loud.

Chime in you guys...
 

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WOW! Same problems as my Weatherby Vanguard in '06.
1. What is the BBl Twist?
2. Scratch on case from Mag?
3. Shut off the gas valve and try it...Manually cycle.
4. Every 5 rounds clean the BBL and retry.
5. Is trigger guard getting more tension at 1/2-1/4" from lock up?
6. Did you check that the BBL is actually .300-308 & the Flash Suppressor is on tight? SA, Inc has made mistakes in the past...So, has Douglas
7. Are you Flinching?

http://riflemansjournal.blogspot.com/2012/01/equipment-30-caliber-barrel-specs.html

http://riflemansjournal.blogspot.com/2011/10/equipment-rare-krieger-mistake.html

Please let us know.....
 

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Several years ago I knew a guy who had a bolt gun made with a Douglas bbl and reported that the gun would group well but the POI would move at random times with no obvious problems found with the rifle. After sending the gun to Douglas they lapped the bbl and the problem went away.
 

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Never attempt to shut off the spindle valve on a Super Match...screwed & glued!
 

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Make sure the gas piston plug is not loosening up as the barrel warms/cools.
Had it happen to my Garands, taught me to double check my M-14 Platforms.

Just a wild guess, but you never know.

What happens if you single load rounds leaving the same mag in..does it happen the same?
 

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It is well known among M14 match shooters, that in many rifles different magazines can effect accuracy.
The magazine is held in by the recoil spring guide and the trigger housing mechanism, so different magazines effect the vibrations of the barrel and the vibrations of the reciever trigger group lock up.

While this may not be that noticeable in regular M14's when you start getting to those guns that shoot @1moa or less it casn cause a difference in not only accuracy but POI.
 

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Discussion Starter · #9 · (Edited)
performance repeated by 2 high masters.

I am very very concerned by the brass headspace change. It seams that the thing isn't locking up fully all the time, something is getting in the way of the bolt fully closing, but at such a small degree that it cannot be easily observed.

I need to some further testing to see why and when the case is damaged. single loads are not as accurate as the first 3 of a clip, but are within 1 moa.

bottom line the gun was once performing at less than 1/2 moa but suddenly went astray. I put 43 rounds, sequencially, in one session, into less than a 1/2 inch group at 100 yds the blah it don't work anymore.

Note, see target. tight groups of 3 are seperated by big distance, should be in same place.
 

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Discussion Starter · #10 ·
Welcome to the forum Jack.

I would be cocerned that what ever is scratching your brass may be scratching the bullet when it's auto loaded from a mag.

Have you ejected a live round to see if the bullet has been damaged?

Seems like there was thread about this a few years ago. I'm just thinking out loud.

Chime in you guys...
I will try to check this out. TNX
 

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I haven't gone through my bucket of brass but 4mils of difference between fired case HS doesn't seems like much to despair about. I'm guessing you're measuring burrs on the case rim and not something real. I can't think of anything that would result in variable headspace that would really matter that much on a target.

Also, scratches, even pretty severe deformation of the bullet, will make essentially zero difference. That's not it.

----

I can't tell from the posts whether heat has anything to do with the issue. Does the rifle always behave well when its cold? Does it return to the original zero if it's cold? If you shoot two different mags with the rifle cold each time, will it shift?

It looks like the issue is almost purely elevation. Are you shooting from position or from a bench? How does it shoot prone with a tight sling?

I'd go through the rifle and check for loose gas system screws, a crack maybe in the gas system/plug, receiver, or stock, loose oprod guide, hanguard clearance at the receiver end, etc. Gas cyl and barrel band fitup. Check for a crack at the ferrule. Remember, there IS something wrong; you just need to find it. So look at everything. Look at the lugs on the trigger guard and make sure they're pulling evenly on the receiver. If it was mine, I'd re-bed it after a very thorough inspection.

Tom Luhmann is down at that end of the state. He might have some insight.


Be sure to count the elevation off the sight when you're done firing so you can be positive that the aperture isn't ratcheting around. Common issue. Scope/mount issues are notorious on the M1A. So be positive that the sights are solid.
 

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I'm having a similar problem with my rear lugged heavy barreled rifle. First 3 shots right on top of each other. Next few 1-1.5" away. If I let the rifle cool, it goes back to same POI accurate 3 shot groups. Repeated multiple times with mutiple match ammo.

Any have more input?
 

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Read a thread recently where there were some stresses preloaded into the barrel due to tightening; I beleve something in the gas system. That put an almost undetectable bend in the barrel. The first few rounds were "dead on" but after a few rounds, the barrel started heating up and aggrevated that "undetectable bend" and accuracy fell way off. Sounds very similiar to what you are describing?
 

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All brass should have a horizontal ding from hitting the op-rod during ejection.

Does your rifle have a rear lug torque screw? If so, torque it to 50 to 55 inch pounds.

After 40 rounds, clean the bore and see if that changes the consistency. Are you using a copper solvent? As far as groups drifting when the barrel gets hot, I would imagine that heavier draw pressure would help.

Tony.
 

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Read a thread recently where there were some stresses preloaded into the barrel due to tightening; I beleve something in the gas system. That put an almost undetectable bend in the barrel. The first few rounds were "dead on" but after a few rounds, the barrel started heating up and aggrevated that "undetectable bend" and accuracy fell way off. Sounds very similiar to what you are describing?

I'm guessing similarly, in both cases. Up ahead of the band where the g/c lives, a heavy barrel can get bent just like a standard barrel can, if the lock is down too tight.
 

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Gas lock is not too tight, however gas cylinder has been epoxied(or silicone, not sure) into place so I can't loosen it. My brass looks the as other M14 type rifles with dents in the usual spots.
 

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I hope it'll come loose - you could put the barreled action in the freezer overnight, in lieu of using heat, then tap the g/c loose.
 

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A few random thoughts - sure sounds like a barrel in desperate need of stress relieveing - send it and/or the reciever to 300 Below for Cryro treatment. Or rebarrel with a new Krieger. Alternately, lap it internally or firelap - at some point you don't have much to lose by radical solutions...

I don't like the idea of gluing the gas cylinder to the barrel - never heard of that. Remove it and mechanically tight, as needed. (peening) Cleaned your gas piston internally lately?

If you suspect bedding, try cardboard shimming the trigger group, or maybe the reciever to change pressure at the ferrule.

Just some thoughts. CC
 

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Barrel IS a new Krieger. Rifle assembled by one of the best, he's done the same thing with all my rifles an they are great shooters. I spoke with him about it and will bring it back, with a test target. Thanks and sorry for the thread hijack.
 

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Actually... Would too tight a flash suppressor cause this too? The FS was on really tight.
 
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