M14 Forum

wiliamr

How safe is it to fire the M14, M1A with the gas system turned off? I have never done it, and have to blow some way undersized cases out. with gas system on, the primers back out about halfway.... HELP

SOCOM42

as far as the mechanical aspect goes, it is perfectly fine to fire with the gas off.

Ammo is another question, i cannot answer.

Young guns

Its safe to fire it with the gas system off, it essentually becomes like a bolt action. I would inspect the head space of your rifle if you are having the primers pop out. Having a proper headspace for your rifle is essential, Or you could have an explossion.
Good Shooting.

wiliamr

Headspace of the rifle is fine. The brass on the other hand.. I did not notice that the sizing die on the Dillon had become loose and had screwed itself down and now all the brass is WAY under head spaced (or over headspaced depending on how you look at it) But the brass in a headspace gauge is about 0.017 shorter that the minimum step. When I chamber a round and close the bolt, the extractor will not even close over the base. Works ok on properly sized rounds (sheeze what a mess) The load is mild 41.8 grains of IMR 4895, cases were trimmed to length before resizing and am using 147 gr practise bullets from Lake City

SOCOM42

Use a bullet puller, scrap the cases

RAMMAC

I wouldn't recommend attempting fire forming cases that are that short. The load you are using is a good load but it's pretty light. I think that the primers appear to be backing out because the load is too light.

Normally the case should stick to the chamber when the powder ignites, the primer will push out until it strikes the bolt's face, and then the pressure will stretch the case toward the bolt's face and reseat the primer. In your case, the load is light enough that the case isn't stretching. But you can't predict if the improperly seated case will hold up to a full powered load or if it will crack catastrophically.

Cases with too short of head space is a worse danger than cases that have too long a head space dimension.

If the head space dimension is too short, the bolt will close but you could have a case rupture or the forces applied to the bolt face and lugs could exceed the design parameters. This could result in damage to the rifle parts and/or the shooter.

Too long of a head space dimension would prevent the bolt from closing and, if the bridge and firing pin are in good order, the firing pin will be prevented from striking the primer and therefore no damage or injury would be done.

jbrooks

I'll make a contrary opinion, even though I respect the views of SOCOM42, RAMMAC and the others who agree with them, based on my experiences with fireforming brass for wildcats, etc.

First, with the gas system closed, it is indeed similar to firing with a bolt action.

Second, the issue of "headspace" can apply either to the front of the cartridge (from the shoulder forward) or the the base of the cartridge. Here is what I mean:

I fireform 9.3 x 62mm Mauser from, say .35 Whelen or 30-06. Tne 9.3mm has a shoulder waay farther forward than the 30-06/35 Whelen, so the cartridge will slide into the chamber and not be held back by the extractor, or if it is, the "headspace is way off any way. So one way I do the fireforming is to neck the 35 whelen case up to 9.3mm and insert a 9.3mm bullet in backwards, so the base of the upside down bullet is jammed into the rifling. Using a normal load, I just fire the round and the case is instantly fireformed to the dimensions of the chamber with absolutely no problems.

Years ago Julian S. Hatcher did a similar thing with the 30-06. He reamed a 30-06 chamber in such a way that it had about 0.025" excessive headspace, and fired the rounds with absolutely no ill effects. (Hatcher's Notebook, Second Edition, 1957, Page 248)

So the issue with headspace is, you can have excessive headspace in the "forward" direction, so long as the bolt sufficiently seals the rear of the cartridge case. That's how wildcatters have made new reounds (30-06 Ackley Improved, etc.)

SO... IF your rifle has proper "headspace" to begin wirh ( that is, will not accept a SAAMI or NATO Field Reject guage, then it is perfectly OK to do what you suggest. But MAKE SURE the gas port is closed and you simply treat the rifle as a bolt action.

The case will form itself back to the chamber dimensions.

HOWEVER... NOT SO FAST....

Since the extractor does not engage the rim, your FP will probably NOT fire the cartridge. PLUS, the extractor will push the case farther in, and my not allow proper forming of the brass when fired.

So I Recommend that you single-load each round, manually inserting the case rim under the extractor and letting the bolt ride home. Very simpe to do. Pull the op rod back with your right hand and slide the rim under the extractor then push the cartridge onto the bolt face to overcome the ejector spring pressure, align the bullet and ride the op rod forward.

I'm pretty sure I'll get hammered for suggesting this procedure, but it will work fine. The extractor will provide sufficient support to the base of the cartridge.

JWB

RAMMAC

You wont get an argument out of me, I'm just saying that I wouldn't recommend doing it because I can't predict how the case will lie in the chamber and if it will be properly supported when the powder ignites. I'm just trying to err on the side of safety since I can't control the original poster's situation if he tries to fire form the cases.

SOCOM42

I recommended discarding the cases based on the statement too far forward for extractor to catch and primers protruding from pocket.

Think of the results of and unseated case and primer expulsion on ignition.

Last but not least case separation around the first shoulder from all the brass moving on the next or following reload.

If he plans to anneal after firing before resizing he could get away with it,albeit with a thinner wall.

Otherwise, jb you are right.

wiliamr

I have given this some thought: I have taken the first cases fired {when I reloaded about 200 cases and discovered this problem and done some headspace tests, and resizing tests. After firing ( I fired 9 cases before I decided I was either going to blow the gun up or injure myself) the first round, and the rifle did not extract the round. I pulled bolt back and case did not extract, First thing I saw was primer sticking about 1/16 or so of inch out of base, second noteable, was extractor did not engage rim, and I could easily pop the round out of the chamber with my finger nail. I resized 4 cases and tested them in my Wilson brass size tester, and my Hornady HS testor.. After firing, there was no sign of web damage, BUT! the brass after resizing did not show any sign of normal stretching. Each case, fit in the two gauges with little play and the case base was expanded enough to not fit the Wilson case gauge before sizing, but after sizing, was within the gauge datum marks. My first thoughts on this was to put about 10 grains of Unique into the remaining cases (oh... there are about 1000 undersized cases) with a 100 gr bullet and fire them one at a time (probably a good excuse to buy a Handi rifle in .308, or a Mossberg in .308), to blow the shoulders out. I think though... that this will stress the cases, and even though I will run them through my annealer (made from and old natural gas space heater turned upside down over a tray of water, to where the flame heats the case mouths about 1/3 of an inch and them tumped over on the side) I think I may have some brass with a serious life issue. Any thoughts

jbrooks

Sounds like pretty typical fireforming. You're on your way. :)

JWB

Al Mack

That's the way it's done, and I haven't heard that excuse for buying another gun before!

Ezekiel

I shoot with the gas valve off, it saves on the life of the brass. If I think some loads are a little to hot like M118, I switch off the gas to save on the brass and oprod.

stoky

Has anybody noticed a difference in point of impact, or group sizes. with the gas system off and on?