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popping primers

Hi there
I was doing some garage testing on firing pin. Loaded some cases with primer only...NO powder. No projectile. The primers came about 30 of their way out of the pockets. This was new brass. They work fine in loaded full rounds. Any ideas please?
 
either that or under pressure load... which there is no load in this case, can cause primers to back out. Empty case and just a primer, with not enough pressure to drive back case against bolt face. For every action, forward in this case only, there is a opposite and equal reaction, not in this case.
 
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Primers are quite powerful for their size . When the gases are funneled down through the flash hole that creates pressure in the primer pocket . That pressure will push the primer out of the primer pocket . It actually happens every time you fire a round but then the pressure builds in the chamber and the case is pushed and pressed back up against the bolt face pushing the primer back in . No bullet no powder equals popped primers .

Interesting fact that some don’t believe can happen . Is you can have to popped primers when shooting reduced loads or at starting charge weights . I have found Hornady load data sometimes gives you such low start charges that the pressure is not high enough to press the head of the case back up against the bolt face after the firing pin hits and pushes cartridge fully foward resulting in popped primers . In that instance there is enough pressure to expand the case sticking it to the chamber wall but not enough to stretch the case head back up against the bolt face . I actually had this problem when testing some 308 loads with IMR 4895 And Hornady start loads
 
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The use of the word “popping” primers in the thread title is misleading and not what should be used to describe the issue. The primers are “protruding” out of the pocket after firing in an empty case, not popping which to the majority of the shooting community means something entirely different.

I have test fired empty rounds with primers many times. Just point the barrel in an empty bucket or trash can in the garage and fire.

For bottleneck rifle cartridges, if your brass is fire formed to the chamber and sized properly, the primers won’t pop out past the rim face when fired in empty brass. But they will protrude after firing on empty new brass, unless of course you have a custom chamber designed to fit the dimensions of new brass.

With straight wall pistol and rifle cases, the brass has no shoulder to headspace from. Therefor the primers will protrude out after firing on an empty case no matter how many firings are on the brass.
 
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Your cases aren't formed yet. Too much headspace can cause that. Won't happen with a loaded round.
Formed cases don't mean that primers won't back out.. Too much HS won't always cause primers to back out, and a loaded round won't always prevent primers from backing out.

loaded rounds under loaded powder charges will and HS, can, yes.. but not always
 
Your cases aren't formed yet. Too much headspace can cause that. Won't happen with a loaded round.
It CAN happen with a loaded round if the case has too much headspace. (not a barrel headspace issue) The round fires, case is shorter than the chamber because it hasn't been fire formed yet, primer goes BANG and backs out of the pocket and sometimes gets pierced.
Cure before the brass is fire formed? Load long with the bullet stuffed into the lands. That holds the case head against the bolt head. And if you "roll your own", make sure you don't push the shoulders back too far and get the same situation again.
 
Excellent method of measuring your headspace! You should keep one or two of those cases with a backed out primer and measure the primer to shoulder, record it and use that measurement to set up your full length sizing dies.

I don't FL size new brass until I've fired it 2 or 3 times and start to experience a stiff bolt close. At that point they are fully fire formed. But this method is for producing the most accurate handloads, and not necessary for plinking or hunting.
 
Hi there
I was doing some garage testing on firing pin. Loaded some cases with primer only...NO powder. No projectile. The primers came about 30 of their way out of the pockets. This was new brass. They work fine in loaded full rounds. Any ideas please?
You didn't mention the type of case you were using. i.e. rimless, belted, etc. This can make a difference due to the way casing is held. On a rifle with shoulder headspace, what you seen is gonna happen most of the time when firing primer only. Belted case...a different story somewhat.
 
that was one of my points, among others !
either that or under pressure load... which there is no load in this case, can cause primers to back out. Empty case and just a primer, with not enough pressure to drive back case against bolt face. For every action, forward in this case only, there is a opposite and equal reaction, not in this case.
 

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