Help, Primers backing out!

D

D-Rock

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Today I went to the range to shoot my very first reloads out of my Yugo Mauser. At first things were going well but when I got to my third batch I noticed that my primers were backing out of the pocket. Upon further inspection I noticed that the primers were backed out very slightly on my lighter loads(43.5 grains IMR 4895). I was using 44 grains of IMR 4895 which is well below the max of 47.5 grains listed in my manual. At this point it was very noticeable. The rifle is mint. Is this an issue of primer seating? I was using a handheld Lee auto-prime and everything felt okay at the time. Some direction would be appreciated as I am anxious to get this fixed and go shooting.:)
 
Typical with low pressure loads.

The firing pin strike push the cartridge case forward in the chamber taking up the head-space.

Upon ignition the case walls expand and grip the chamber walls and the primer cup backs out slightly until it touches the bolt face.

As the pressure peaks the case will push back against the bolt face and re seat the primer cup.

If the pressure is too low the case will not overcome the resistance of the case walls against the chamber walls and the primer cup will remain protruding slightly.
 
Is it necessarily harmful if primers do back out with low pressure loads. I have always been told that primers backing out indicted gas leakage. What confused me was that as the load increased from 42.5 to 43.5 to 44 grains the primer back out became more prominent. This was only noticed on two pieces of brass though.
 
Does it happen with factory ammo too? If not, the headspce is likely ok. Doesn't hurt to check it though.
What brand of brass? Some brass is softer than others.
"...became more prominent..." More powder gives more pressure. I'd pitch the two pieces that are giving you grief. The primer pockets may have opened a bit.
 
D-Rock said:
Is it necessarily harmful if primers do back out with low pressure loads. I have always been told that primers backing out indicted gas leakage. What confused me was that as the load increased from 42.5 to 43.5 to 44 grains the primer back out became more prominent. This was only noticed on two pieces of brass though.
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When I've had primers backing out I've usually found that a small powder increase of .5 to 1 grain fixes the problem.

Another sign of really low pressure is smoked cases, where the case isn't even expanding enough to seal on the chamber walls.
 
Domestically loaded 8mm ammo is quite mild and amy show the same symptoms. If you want a true test of factory ammo in that rifle, find some Norma or RWS 8x57JS ammo and try that. It is loaded to Eurospec standards, and will more closely reflect the potential of the rifle/cartridge combination. My bet is you won't see any primers backed out with that ammo. I have a Remington 700 Classic in 8x57, and Winchester factory ammo fired in it backs the primers out ever so slightly, just enough so the fired case will "rock" a tiny bit when placed upright on a table. My reloads and the Norma (and RWS) ammo do not show this at all, and trust me, there is NO headspace issue with this rifle. Regards, Eagleye.
 
I've shot federal, Remington and Igman stuff and have never had this problem. I was using brand new Remington brass. Hopefully I can get to the range tomorrow and try some heavier loads.
 
You know, the same thing exactly happened to me with my 30-06 Heym. With the lighter loads, brand new REMINGTON brass -- there was primer creep. With once fired Federal brass (in another 30-06) -- no creep in the Heym. Reloaded (only partially resized) the Remington brass with good strong loads, no creep (just flattening when you get too hot).

Never, ever happened to me before -- maybe it is the remington brass..?
 
gunster said:
Have your rifle checked by a gunsmith for excessive headspace. Primers backing out is not a primer seating issue.
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This is the best advice so far! With the correct headspace, you should not have noticable primer movement. You may try compensating for borderline (big) headspace using a different bullet seating, but have your gun fixed if it got to that point.
 
I was able to squeeze in some range time and there was no primer creep with the heavier loads that I made. Used a few different brands of brass and it is all good now. Thanks for all of the advice.
 
Unless the case is such a close fit in the chamber that it is locked in place, the primer will always back out. Unless loads are on the light side, the primer is reseated when pressure builds inside the case, so it is never noticed. If you want to experiment, just pop a primer in an unloaded case. It will usually be slightly proud of the case. If the primer is absolutely flush, that case is a very close fit in that chamber.
 
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