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Discussion Starter · #1 ·
There was a reprint of an AR article on slam fires included in the box with my new rifle. I stopped on the way home and bought a box of .308 Winchester SuperX 180gr Power Point hunting ammo, being a total noob and not having read the article.

I don't want to risk using it and intend to wait for my Milsurp to get here, but wondered if y'all can tell me whether it's really risky to use the commercial hunting cartridges.
 

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Keep in mind while the slam fire issue is important to be aware of, you also risk damaging you rifle using ammo that does not match the pressure curve the gas system was designed to operate with.
 

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I have never personally experienced a "slam fire", and like you, I never want to.

You are right to just wait for the correct ammunition.

FYI, I have heard that the greater risk, when firing .308 win. cartridges in a semi-auot chambered for 7.62x51mm, is overpressure in the chamber.
 

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I'm familiar with that factory hunting round. It's SAAMI spec, no peculiar sensitivity to the primer. I don't think you're in danger of a OOB ignition with a clean chamber. It's loaded with a slower-burning/higher-pressure-cooking powder, however, like 4350, and would be better shot in your bolt-action rifle.
 

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Spoke with SA Tech Support several weeks ago and I was told that the 180 gr. Winchester round I was asking about was the maximum safe load my SA NM M1A
could safely handle without risk of over-pressure. Still... I'm gonna put those 280 rds in the back of my ammo box for use in a future NEF Handi-Rifle I plan to get this year, and I won't use the 180's in my NM unless a dire emergency happens.

I was glad to hear I could use it, but with so many more safer loads, I don't want my rifle to undergo more stress than is neccesary.

Peace - Patrick <><









,
 

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Ive never had a slam fire on a free moving firing pin setup like the M14 or AR-15, as stated id be more concerned about exceeding the gas system specs on the 14 than a slamfire
 

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I have an AR-308 Galil and experienced a slam fire many years ago. This was an early model that had a floating firing pin.

I was using a reload that my brother put together using a once fired military case, W-W 748 powder, and a Winchester 147gr. FMJ-BT bullet. We discussed it afterwards and he admitted that he may have used a large pistol primer instead of a proper rifle primer. He had spilled some of each while reloading and did not dispose of all of them like he should have. You cannot tell a large pistol from a large rifle primer by sight.

The round was stripped from the magazine but detonated before it was fully chambered rupturing the brass and blowing the pieces out of the ejection port. The bullet was lodged in the barrel just forward of the chamber and had to be tapped out with a cleaning rod. The strangest thing was that the anvil of the primer (the 3-sided piece of metal you see on the "inside" of the primer) was pressed into the side of the bullet. How it got there is anyone's guess.

Fortunately no one was injured and the rifle sustained no damage.

Shortly after this incident Magnum Research (the USA importer at the time) recalled all Galils for the addition of a firing pin spring. Perhaps my slamfire was not the only one.

Needless to say my brother and I both learned to keep rifle and pistol primers separate. I never experienced another slam fire with the Galil (especially after the recall) or either of my M1A's.
 

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I've seen two, both in M1's. I was two lanes down on one at Camp Perry, and saw another intentionally set off. Neither rifle was damaged, and the projectiles cleared both barrels, but the sight and sound will get your attention.

You'll more likely get them in warmer weather (hot, humid conditions), than cooler. You'll also more likely get them when loading single rounds directly into the chamber, bypassing the clip/magazine. Stripping the round from the clip/magazine causes the bolt to be retarded ever so slightly.

There's a belief out there that military ammo, with harder primers, may keep slam fires from happening. I was schooled, in the 1960's, that it was single-loading that caused the problem.
 

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Ive been using Federal Power shock out of mine and with no worries.

I am never afraid to single-load my M1A because i always let the bolt slam home from HALFWAY down, if not just riding it forward till she stops, then snapping the bolt into battery with a tap.
 

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If the receiver bridge (""safety" bridge) is in spec, and your primers are fully seated, the possibility of a slamfire is nil. Assuming of course the firing pin is working properly.

The FP tip stops between 0.003" and 0.02" away from the primer in a correctly dimensioned receiver, before the bolt rotates into battery. So a "high" soft primer is problematic. But factory ammo should be OK.

JWB
 

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The ammo you mention is intended for a bolt gun. Your gun will shoot it, but you could damage your rifle doing so. The burn rate is more than likley to slow for a gas gun. Also most feel 175 grain bullets are the heaviest that are safe fore the M1-A.

Slam fires are caused by dirty chambers and primmers that aren't set below the flush line. You should be good to go with most mill surp ammo.

Sorry to hear you caught this terrible desease, to bad no cure.

I almost forgot there is also the double tap. Caused by weak grip, have a firm grip on your rifle and you shouldn't have this happen.
 

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There are a lot of factors involved in a slam fire besides the primer type.

For the first few years I reloaded for my M1A I used Federal bench rest primers with no issues. Way back up in the hills of WV I didn't have access to the internet to tell me it was bad to use those primers (there was no internet in the late 70's/early 80's). After the store I got my primers at stopped carrying Federal primers I used standard CCI large rifle primers with no issues.

A few months back, when I first reloaded for my .300 black out in my recently built AR15 I used Remington small pistol primers to light up the first 50 rounds I loaded since I was using H110 powder at only 17 grains behind a 150 grain bullet. I felt it was very similar in amount of powder and bullet weight to some magnum pistol loads so I used a pistol primer - no issues with the first 50 (fired in an AR15 by the way).

Ever been involved in an industrial accident investigation? I have. Several. You spend many hours over several days meeting, talking, researching, observing and end up (quite often) developing new tools, new methods, revising existing tool/methods/procedures or even raw materials - when you never really find out the true root cause. It could have been this, or this, and that, or something else, or maybe this contributed, etc., etc., etc. In the end you have several "maybes" with all kinds of ways to prevent these possibilities that had nothing to do with the root cause.

I will never personally "test" the theories by making bad reloads on purpose to see whether or not high primers, dirty primer pockets, dirty chambers, gummed up firing pin channels in the bolt, etc. result in a slam fire. I just know that so far, with my reloads and my rifles I've not had an issue in M1A's, M1 Garands or AR15's.

Some day I'm going to start my "list" of things that I've done/seen that, according to the internet, will result in instant destruction of you gun/car, etc.

If for no other reason that you need to be sure your rifle will operate correctly when you really need it - keep it clean. If for no other reason than accuracy and consistency, make your reloads "right", again, so that they do what you need them to do when you need them to do it.
 

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Discussion Starter · #17 ·
Thanks to all

Thanks everybody for the responses. Y'all covered everything I was wondering about and several things that never occurred to me. The info about slow burn propellant overloading the gas system is one that I couldn't have thought of since I had no solid understanding of the design. The info about the need for the bolt to slam home from at least halfway addressed the thought I had about single loading a round or soft loading one from the mag by gliding the bolt down by hand.

Now I know that a slam fire isn't the only danger to my rifle from non-spec ammo.

Great forum. Y'all have helped me a lot with the input.
 

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4000+ rounds through my M1A, never a slam fire. Mostly commercial and hand loaded ammo with commercial components.

I never chamber load, always load the magazine even when single loading.

I saw a slam fire on range once in an M16 when chamber loaded.

Cheers
 

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I thought the M14 gas system was much improved over the M1 to have a pressure relief type of system to address different burning rates of propelants? If not, then I am learing something new here. I still only load BL-C(2) for my 147 BTFMJ and 172 grain match bullets as that was one of the original powders.
 

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Burn rate issues have been discussed a lot here. Do a search and see what you think. From what I have read and the opinions of respected members here, yes the m14 system is more tolerant, but the speed of the impulse is as important to consider as the volume of gas allowed into the piston before the excess bleeds off. That is my simplification based on the info I have seen, if it's incorrect I'm sure someone will adjust me.
 
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