primer preasure reading

[dw1784]

Gents,
here's a sampling of range brass my bro picked up for me.



I've only read about "primer preasure reading" in the reloading books and never actually experienced it for myself.

I've arranged them based on deformation and height(depth) of striker indentation, correlating preasure and deformation. Right to left- low to high(I think).

From the first on the right, is that punctured primer from too light a load? preasure wasn't enough to re-seat the cup back into the pocket?

2nd from the left, based on the appearance of the headstamp, could the preasure be high enough to cause flattening the headstamp? The case might've been reloaded many times, an incremental deformation with each "hot load"?

last from the left, the preasure was too great causing the cup material to deform and "flow" out of the pocket? or maybe the primer wasn't seated fully?

these brass were taken from a tactical rifle range, so I'm assuming they were fired in semiauto rifles and not bolt action rifles. I'm assuming they are home reloads and not commercial new mfg or commercial reloads(let's hope not). Thanks for your input.

[ocabj]

Once you pierce a primer, you should change your firing pin. Piercing a primer can deform the firing pin, making future pierced primers more likely to occur.

The rest of the primers (except the one on the far left) look like they were fired after the pierced primer due to the weird 'nipple' characteristic in the center of the primer hit. Again, this is why you should change firing pins after a pierced primer.

Can't tell you what's up with the one on the far left.

[Technical Ted]

Can't tell you what's up with the one on the far left.

Scary looking isn't it?

[ocabj]

Scary looking isn't it?

Definitely. I've never seen a primer like that before.

It's LC, but it looks like a reload since new USGI ammunition usually has gold/bronze colored primers.

[phish]

I'm not familiar with that headstamp, who makes that brass?

Yeah, the one on the left is freaky looking, but I have a feeling the guy hot-rodded those loads to NATO pressures and shot them out of a .223 chamber with a shorter throat.

I've seen primers like that from XM193 ammo that was shot from a factory boltgun chamber. I don't know exactly what causes that little mosquito bite in the center of the primer, but, using WAG-fu:

1.) pin strikes primer
2.) case obturates and slams onto the back of the boltface
3.) case contracts a little, but the primer cup is still malleable from the heat
4.) center of cup is still stuck to the pin, thus causing the dimple

[dw1784]

don't know who makes it, phish. My bro picked it up at a range for me. I sorted them out as there's a lot of these reloads and seems whoever reloaded them was kinda "sloppy" with his/her load.

the last round with the messed up primer had an enlarged primer pocket I think. I was able to pick off the spent primer with my finger nail. I guess I should keep an eye on that when I start reloading 223's in qty.

thanks for the input guys
I'll be sure to include a spare bolt in my next outing.

[Fjold]

the last round with the messed up primer had an enlarged primer pocket I think. I was able to pick off the spent primer with my finger nail. I guess I should keep an eye on that when I start reloading 223's in qty.

That is a good indication of the brass being reloaded too many times or of it being overloaded. I buy the 100 count bags of brass and reload them exclusively as a group. I reload them the same number of times until I discard them. If I get more than two brass cases that the primers pockets feel noticeably looser than normal. I discard that entire lot of cases because they are at or near the end of their useful life.

IMHO Left to right:
1.) high pressure forced the primer back out of the case and smeared it when the bolt was opened. Check the headspace on this gun, it looks bad.
2&3) High pressure the edges of the primers are sharp where the the primer has flattened. I think #3 had the higher pressure.
4&5) show firing pin cratering which is usually a sign of high pressure or an enlarged firing pin hole or worn firing pin. Check the bolt face and firing pin on this gun. Both primers are moderately flattened.
6.) pierced primer, check the firing pin for damage along with disassembly of the bolt for pieces of the primer cup. The pressure wasn't excessively high, because the primers are not flattened at all. There wasn't enough force to push the case hard into the boltface.