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Old January 14, 2021, 08:32 PM   #1
mapsjanhere
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M14 with ammo issues

I have a M14 style semi-auto that shoots great with Lake City surplus - which I'm out off and yeah, can't find anywhere. Most civilian production 308 rounds have failure to feed issues, looks like the bolt isn't moving far enough back to cleanly eject, 3-4 per magazine. Is this due to civilian ammo being softer loads, or is the military brass less sticky? Any suggestion for a brand to try to get around this?
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Old January 14, 2021, 08:59 PM   #2
rc
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Sounds like your gun is cranky with ammo. Are you shooting soft points? Are the noses hanging up because of exposed lead? M1 and M1A are supposed to be very picky on the correct powders to work. Have you chronographed the loads. Tried different magazines? Around 2600 to 2750 fps with 150 grain bullets is about right. I would think most commercial ammo is using powder that will work in M1s but who knows. What load are you having problems with?
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Old January 15, 2021, 08:58 AM   #3
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As a guess: most factory .308 ammo uses slower powders than that recommended for M14s. This tends to increase "port pressure," the residual combustion chamber pressure at the point where the bullet clears the gas port. If you are over gassing your rifle, the bolt may move faster than designed. That, in turn, can lead to a number of problems, of which consistent reliable ejection may be one.
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Old January 15, 2021, 09:00 AM   #4
Bart B.
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The bolt is "short stroking," port pressures are too low; try cleaning out the gas port.

Last edited by Bart B.; January 15, 2021 at 09:20 AM.
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Old January 15, 2021, 01:46 PM   #5
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Quote:
Most civilian production 308 rounds have failure to feed issues, looks like the bolt isn't moving far enough back to cleanly eject, 3-4 per magazine.
Those are two different issues,
some questions...
1) what is "most civilian ammo"?? Meaning, what brands/loads have you tried?

2) What is "cleanly eject"?? Cases are extracted but not ejected?? Does the rifle jam with a fired case in the action? Something else???

To be clear, extraction / ejection problems can result in feeding problems, but you can't have a "feeding problem" until you have finished the ejection cycle without issues.

3) specifically, what is your "M14style" semi auto rifle?? Make/model...?

Quote:
If you are over gassing your rifle, the bolt may move faster than designed. That, in turn, can lead to a number of problems,
It is extremely difficult to "overgas" an M14/M1A. Unlike the direct impingement system of an AR, and even unlike the GI piston system of an M1 Garand, the M14 piston system is "self regulating". What this means is, essentially, that when the piston starts to move, additional gas pressure from the barrel is cut off, and dumped outside.

Based on what you've told us, I'd agree the most likely thing is short stroking. Clean the gas system, reassemble properly, and don't oil it. That's a first step, and may be all that is needed.

IF you don't have the manual for your rifle, get one. Clean and properly lube the rifle and try again, If you still have a problem, pay close attention to exactly what is happening, and when. Come back with that info and we can try to help figure it out.
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Old January 16, 2021, 07:07 AM   #6
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It is true that it will be more difficult to over gas an M14 than an M1, it is far from impossible. The metering function of the M14 is based effectively on time (of gas port opening) rather than gas tube pressure per se. That is why an M14 will tolerate a port pressure somewhat above the 7 kpsig standard commonly recognized for M1s. It does not, however, totally eliminate the potential for over gassing as a result of ammunition loaded with slow burning propellant.

I thought about short stroking caused by a fouled piston, but isn't it likely that, if that were the issue, the rifle would also short stroke using mil spec ammo?
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Old January 16, 2021, 12:18 PM   #7
4V50 Gary
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Ammo should be w/in NATO spec. M-1 Garands and M-14s are designed to work w/in certain pressures/energies.

BTW, for fun I once tried steel cased ChiCom and lo, not surprisingly they didn't extract.
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Old January 16, 2021, 02:21 PM   #8
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Quote:
It does not, however, totally eliminate the potential for over gassing as a result of ammunition loaded with slow burning propellant.
Very little will totally eliminate the potential for people doing stupid stuff with, and to their equipment.

You can say the M14's system is based on time, but I say its based on movement, recognizing that movement takes time. Unlike many other systems when the piston moves enough, gas pressure from the barrel is cut off. This limits the amount of pressure pushing the piston, unlike some systems that maintain pressure until pressure drop due to bullet exit. Additionally, the M14 system can be turned off and on easily, a feature not found on many other rifles.


Quote:
I thought about short stroking caused by a fouled piston, but isn't it likely that, if that were the issue, the rifle would also short stroke using mil spec ammo?
it may not be short stroking, the OP has not yet responded with a precise description of specifically what is happening. I got the impression it worked fine with GI ammo, and when he ran out of that, started shooting commercial ammo and that's when his problem(s?) began.

Properly cleaning and lubing the rifle (and putting it back together correctly) is just a basic first step advice, like "close the window then open it back up and see if it runs" or "reboot your system and see what happens".

It MAY or may not solve the problem, but it gives a base standard on which to troubleshoot.

Same idea with "try different ammo". And the idea of only changing one thing at a time.

The OP has given us only some basic info, so we can only give a very general response. So far.

Lots of things are possible. Some are more likely than others. The more we know in detail, the better we can diagnose and offer suggestions.
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Old February 1, 2021, 01:53 PM   #9
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Sorry for not responding faster, had an unfilled bow tag and still haven't made it back to the range to get some footage of the error.
All the ammo I tried was FMJ, I haven't put any hunting loads in it. Mainly Winchester white box, and some that were sold as LC surplus but turned out to be factory reloads. I haven't done much in the lubrication department other than basic Remington either. I get back to you when I get my hand on more ammo to justify a range trip (what right now is a challenge).
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Old February 1, 2021, 06:57 PM   #10
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Am wondering just which "M14 style" rifle you have and do you have the owner's manual??

Also I'd recommend getting a copy of the old Army FM (field manual) for the M14. I forget the number but it shouldn't be too hard to find. This will give you the GI recommendations for lube and maint, which are generally applicable to all the M14 pattern rifles.
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Old February 2, 2021, 01:10 PM   #11
mapsjanhere
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Sorry, all I was told is that it was made as a one-off receiver by Bill Ruger for some trials and later completed with a military parts kit. I will track down the manual.
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Old February 2, 2021, 03:02 PM   #12
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A few decades back, Ruger announced they were going to make a Mini-14 type rifle in .308 Win. They called it the XGI.

It looked like a sporterized M-14 but there were mechanical differences, and it was not a true M-14 pattern rifle. Ruger never put it into production. They made a few prototypes, and then dropped the idea. According to the buzz at the time, Ruger couldn't get it to A) meet their accuracy standards, or B)work reliably, and so refused to market an "inferior product".

For what ever reason, Ruger never put it into production.

IF you have one of those prototype receivers and someone later built a rifle on it, you have a truly rare oddball, and we'd be very interested in pictures and all the verifiable history you have on the gun.
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Old February 3, 2021, 10:23 AM   #13
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Mapsjanhere,

Commercial ammunition is loaded to not exceed SAAMI peak pressure limits and, except for special loads, to have a velocity that meets SAAMI ranges that were ±90 fps in the 1992 SAAMI standard, but which have no tolerance limits in the newer 2015 standard. By comparison, the NATO-compatible military loads that have both the crosshair and four-leaf clover symbols on the case heads are required not only to stay within peak pressure limits but also to stay within gas port pressure limits and to produce a velocity that is ±30 fps from the test barrel. If the velocity is not met or the bullet is not a standard weight, only the crosshair symbol is used to show it passes the two pressure requirements and will function NATO arms correctly but may not have points of impact that match standard sight calibration marks or other exterior ballistic expectations.

It sounds like, in your case, your gun wants you to meet the military gas port specs. This can be done pretty easily if you reload. BL-C(2) is the canister grade version of the same powder used in M80 Ball ammunition. IMR 4895 works for that purpose, too, and I've shot a lot of it and 4064 through and M1A behind 168-grain and 175-grain match bullets. If you are trying to shoot lighter bullets than 150-grains, that can make the gas impulse too short, even if the pressures match.
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