Enlarged primer pocket

tomL

tomL

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I have some brass that the primers go in quite easily. The pocket measure .211".
The loaded ammo. seem to shoot fine without any undue gas escaping around the primer.
In time I am sure the pocket will enlarge further. At what point (size?) would it be unsuitable for reloading?
Thanks. Tom
 
Being new to this reloading game, I have also wondered this. I have noticed quite a few times how much easier a primer would go in using my Auto Prime, but the brass I was using had only been fired twice, and not hot loads. Would that just be primer pockets that are manufactured out of spec ??
 
heavyBullet said:
Being new to this reloading game, I have also wondered this. I have noticed quite a few times how much easier a primer would go in using my Auto Prime, but the brass I was using had only been fired twice, and not hot loads. Would that just be primer pockets that are manufactured out of spec ??
Click to expand...

No. Primer pockets, as well as the entire case, is manufactured to very close tolerences. It is important that the primers fit quite tight.
Many years ago Jack O'Connor gave the following advice. he said if he could push the primer in with his thumb, it was too loose and he would discard the case. I discard the case while the primer still goes in a bit tighter than could be done with the thumb.
Pressures that exceed what the case was designed for expand the pockets, as well as several firings of rather high pressure loads.
 
I suppose you are talking rifle - I've noticed that Remington primers tend to be loose.

Be very careful when cleaning pockets - no need to ream them out - the tiny lee tool is easy on the pocket wall. You really need only clean the bottom.

Magnum primers tend to stick in better - don't use them without doing homework first - pressures do go up some - and note that they are thicker, so don't show pressure the same as thinner primers.
 
Being new to this reloading game, I have also wondered this. I have noticed quite a few times how much easier a primer would go in using my Auto Prime, but the brass I was using had only been fired twice, and not hot loads. Would that just be primer pockets that are manufactured out of spec ??
Click to expand...

Not hot loads according to one manual,or according to the max load that you have worked up in your rifle?Some loads listed in manuals actually produce pressure that is above the SAAMI pressure in certain guns.

When I owned my 300wby,I bought factory loads to build up a supply of brass.However after discovering that the primer pockets were quite loose after only a single firing,I pulled the bullets in the rest and the brass lasted much longer if the factory loads were not fired.

If the primer pockets are too loose to use after five firings of the same load,the load is too hot for the gun.

Magnum primers tend to stick in better - don't use them without doing homework first - pressures do go up some - and note that they are thicker, so don't show pressure the same as thinner primers.
Click to expand...

The flatness of fired primers is not an accurate way to judge pressure.
 
I see toml shoots a 270 Weatherby Magnum - so this is nothing to ignore - pressures almost certainly are running too high.
Click to expand...

If the primer pockets are loose within a few firings,I would be concerned with any cartridge,magnum or not.
 
Time to betray my ignorance, again. Upon firing, would the primer cup not expand to grip the sides of the pocket similar to the way the cartridge expands to grip the chamber walls ? These do ignite first and the cups are pretty thin.
 
Last edited:
H4831 said:
No. Primer pockets, as well as the entire case, is manufactured to very close tolerences. It is important that the primers fit quite tight.
Many years ago Jack O'Connor gave the following advice. he said if he could push the primer in with his thumb, it was too loose and he would discard the case. I discard the case while the primer still goes in a bit tighter than could be done with the thumb.
Pressures that exceed what the case was designed for expand the pockets, as well as several firings of rather high pressure loads.
Click to expand...

Once again you are right on Bruce. If you can push a primer in with thumb pressure, the pocket is way too loose. But if you are seating the primer with mechanical leverage, as long as you can feel some resistance you are good to go.
 
CCI primers tend to be slightly larger in diameter and tend to stay tighter for an extra firing or two. As for primer cups expanding to fit the primer pocket, it doesn't seem to happen. The explosive mixture in the priming cup is very small and very fast. It is difficult to sort primers by weight because variances in the weight of the cup and anvil would mask variances in the priming charge, that is how small the priming charge is. Once the primers get very loose, you could experience flame cutting of the case and of your bolt face. Suffice to say that attempting to extend a cartridge case beyond its practical life span is unsound.
 
Thanks guys. Now it makes sense.
The brass are once fired factory ammo. cases and they came with the rifle. As the previous owners both stated velocity 100-150 ft./sec higher than what I can obtain with manual max. I can deduce that perhaps the factory loading is really hot and causes some of the primer pockets to expand beyond the expected amount.
I shall most certainly discard the ones that I feel no resistance with the insertion of the primers. Tom
 
Boomer said:
Once again you are right on Bruce. If you can push a primer in with thumb pressure, the pocket is way too loose. But if you are seating the primer with mechanical leverage, as long as you can feel some resistance you are good to go.
Click to expand...

Ok, thats a good trick to know.


When I owned my 300wby,I bought factory loads to build up a supply of brass.However after discovering that the primer pockets were quite loose after only a single firing,I pulled the bullets in the rest and the brass lasted much longer if the factory loads were not fired.
Click to expand...

I just bought some new brass yesterday, so I will start loading these first, and see if the same thing happens again.
 
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