Primers backing out

[rec3648]

What might cause a primer to back out of a recently loaded cartridge? The load is for my 270 Win. using 55 grains of imr 4350, cci 200 primers and nosler 130 grain accubond bullets. This is not a compressed load, the brass are new winchester, the primer pockets hace been uniformed, the primers feel tight when seated, the bullets are crimped with a lee factory crimp die.

 

[GooseGestapo]

In box before firing, or during firing ??


55.0gr is HOT. It's max or above on some newer manuals.

I've found that 54.0gr is about tops for several .270's I've loaded for. I suggest you seat the bullets a little deeper and/or reduce the charge 1-2.0gr.

If backing out before firing after being seated, you are expanding the pockets too much during the "pocket uniforming". The air pressure of seating the bullets is forcing them out. Also, during firing, the oversize primer pockets will allow gas leakage that can damage the bolt face...

Except for some bench-rest competition loading, uniforming the primer pockets is wasted time and effort. Uniforming the flash-hole may help if you got a bad batch of brass, however.... Ditto neck turning, unless you have some really bad brass or a custom/tight throat on your rifle....
BTDT.....

What kind of rifle are you firing them in that requires you to crimp?? Bolt action's and single shot rifles don't require crimps and isn't generally recommended for best accuracy. I suspect you'll see an improvement in accuracy if you don't crimp.

 

[buck460XVR]

Excessive headspace can also cause primers to back out.

 

[rec3648]

new commer, should have done a quick reply

 

[rec3648]

Primers backed out in the box. Thanks for the tip on uniforming primer pockets. I'll think twice before doing in again. I'll try some loads without the crimp. I have moved on to H4350 and Barnes TTSX 130 gr bullets with much improved acuracy. The rifle is a Kimber Montana with a 24" barrel.

 

[Walkalong]

A primer is very soft brass. I just do not see it backing out after being seated, not even in a primer pocket that is tapered a hair instead of being square.

 

[Mal H]

How far do they back out of the pocket? Are they now above the base of the case?

Is it possible they weren't properly seated originally and you noticed it a while later? That is a more plausible explanation than having a properly seated primer physically back out of a new case.

 

[gamestalker]

Never heard of primers backing out of the case head before being fired? My guess would be they haven't been seated all the way, .004" below the case head. Sometimes when we have been at the bench for several hours we tend to over look quality control. I always inspect my cartridges after every reloading session to prevent over sights from making it to the range.

I use a lot of compressed charges with brass that has pretty loose primer pockets, and still haven't experienced that issue? Is there any possibility that you might have a bit of moisture, be it lube or other solution in the case that is expanding in a hot enviroment?
GS

 

[rec3648]

Never heard of primers backing out of the case head before being fired? My guess would be they haven't been seated all the way, .004" below the case head. Sometimes when we have been at the bench for several hours we tend to over look quality control. I always inspect my cartridges after every reloading session to prevent over sights from making it to the range.

I use a lot of compressed charges with brass that has pretty loose primer pockets, and still haven't experienced that issue? Is there any possibility that you might have a bit of moisture, be it lube or other solution in the case that is expanding in a hot enviroment?
GS

Thanks gamestalker. I had three cases out of a hundred new winchester brass that I had missed when uniforming the primer pockets. I pulled the bullets,tried to reseat the primers, they would not go any deeper. I carefully deprimed the cases, uniformed the pockets they seated perfectly just below the case head.