What causes a popped primer?

[Chaotik]

I should clarify.

Nothing has popped yet.

I do have a bunch of primed brass that I've discovered has ~ 1/3 of the primer pockets that the 'no go' side of the primer pocket gauge from 21st Century will go in 1/3 to 1/2 of the way.
The brass is all bumped 2 thousandths from the chamber headspace. The loads I'm using are 52K to 56K [according to GRT].
Before starting to prime this lot I knew the primer pockets were getting looser, but only recently tested a some with the primer pocket gauge. This lot of brass is all primed with Unis Ginex SRP to account for the loosening pockets. But, with the testing I just did [just over 100 unprimed cases], I'm beginning to wonder how many of the primers are going to come out.

Do I have it right that, in an ar15, when the powder is first ignited, the case is forced back against the bolt face, yes? When the bolt starts to open does it retract from the base of the case so that there is room for the primer to be pushed out [assuming there's enough pressure left in the case].?

21st Century sells a primer pocket no go gauge? Interesting.... do you have a link?

 

[RegionRat]

Probably meant the ones by Ballistic Tools?
https://ballistictools.com/store/small-and-large-primer-pocket-gauges

 

[markm87]

Primer pocket gauges epitomize lunacy. No offense to anyone who uses this type of thing, but at some point you have to seat a primer and make a decision.

The last time I had really loose pockets, I dropped super glue on the primer edge after seating the primer and recycled the brass after that final firing.

 

[jelenko]

21st Century sells a primer pocket no go gauge? Interesting.... do you have a link?

Sorry. Ballistic tools https://ballistictools.com/store/small-and-large-primer-pocket-gauges

 

[big5ifty]

The primers are well rounded, there is no sign of an ejector swipe.

I misunderstood. It assumed a popped primer meant an ejected case with the primer missing.

If you're on 8 firings and the primer seating just feels easier, to me it means the brass is near the end of it's service life, not that there's a pressure problem.

 

[Old Navy]

The primers are well rounded, there is no sign of an ejector swipe.

I did forget to mention they've been fired a total of 8 times; 7 times by me. It's only in the last two - i.e., the 7th and 8th firing - that I've noticed primers are seating easier.

Total lot size started at 5,000.

Trash them. .223 brass is cheap.

 

[jelenko]

Trash them. .223 brass is cheap.

Right.

Right after the next firing - they are already primed.
I've gone through 60 loaded rounds and no primers have come out yet.
Using just for practice.

 

[markm87]

Good Gried I was back in the popped primer mess again Saturday. Worked up a load of 22.8 gr N135, 77 gr OTM, and new production CCI 41s.

Everything checked out two weeks ago with a great SD and a velocity of 2750 +/- out of a 20" bolt gun... Not screaming hot, but a stout load no?

So I load up a 150 round and had like 5 popped primers out of 30-40 rounds fired in the AR-15s 2-3 different guns. So sick of these primers making my range time hell.

 

[Hoser]

Good Gried I was back in the popped primer mess again Saturday. Worked up a load of 22.8 gr N135, 77 gr OTM, and new production CCI 41s.

Everything checked out two weeks ago with a great SD and a velocity of 2750 +/- out of a 20" bolt gun... Not screaming hot, but a stout load no?

So I load up a 150 round and had like 5 popped primers out of 30-40 rounds fired in the AR-15s 2-3 different guns. So sick of these primers making my range time hell.

Popped as in blown out of the case or pierced like a drill bit hit it instead of a firing pin?

If pierced, check your firing pin tip. It might have a sharp edge.

If popped/blown, there is a much bigger issue. Depending which 77 gn bullet you are using you could be over max. Just because it works in a bolt gun does not mean it will work in a gasser.

 

[jelenko]

What is the COAL?

 

[RegionRat]

COAL = Cartridge Over All Length

 

[markm87]

If popped/blown, there is a much bigger issue. Depending which 77 gn bullet you are using you could be over max. Just because it works in a bolt gun does not mean it will work in a gasser.

Popped.

I've been battling these primer for months now. I had the same load with Wolf primers running below 2700 fps. So 2 weeks ago I ran a test load with the CCI 41s KNOWING I'd get at least 50 fps bump.

They ran great at that time. No issues. I wouldn't even mess with these primers, but I have thousands of them, and I'd like to ration out my remaining Wolf SRMs if possible.

The repeating theme with these primers is that I get swipes and poppers even though the velocity doesn't reflect it. The primers appear to be really tweaking the burn/pressure curve.

(also... I did chamber brush my ARs to address the possibility of a carbon ring as a factor)

 

[jelenko]

COAL = Cartridge Over All Length

Right. I was wondering what the COAL is of the rounds the OP is using.
Maybe they are loaded long for the bolt action but too long for the AR.