Odd looking primer strikes

Status
Not open for further replies.
M

Mosin-Marauder

New member
I was looking at some primer strikes on some fired 180 grain winchester 7.62x54R. There are some that look a bit odd. I'm not really sure why. There are a few that look like this.


If you can't see it from the photo, there's this small circle around where the firing pin struck that almost looks like it's swelled a bit, though then again it doesn't. All of the other primers look like this. I haven't found any split cases or anything. What could this be and is it bad? Thanks for your help.
Mo.
 
Are you referring to "cratering", with a ring of raised primer material around the firing pin indent?
Denis
 
Only if extreme.
Shoot the gun, Mo, don't worry about it.

It's basically AN (but not necessarily a CRITICAL) indicator of a pressure increase with a load in a given gun.

Doesn't look worrisome in the photo on my screen.
Happens occasionally.
 
Primer "reading" is a horribly in-exact science with a laundry list of pitfalls. (Primer reading is examining the fired primer and attempting to come to rational and accurate conclusions about what you see and what it MIGHT mean)

When the round discharges, the cartridge case fills with pressure and that pressure does every single thing it can think of to ESCAPE. We use the pressure to move the bullet which is the path of least resistance for that pressure to exit.

But the pressure continues to go everywhere it can go, and it fills that primer cup from the INSIDE and it makes the primer cup want to swell and "tattoo" itself against the face of the bolt (or slide or breech face) and the associated firing pin hole.

In handloading, in one size... we get to pick between "regular" and "MAGNUM" primers according to need. A "MAGNUM" primer offers a longer flame duration that helps to ignite certain powders that might resist a proper ignition. What some don't also realize is that MAGNUM primers also offer a thicker primer cup that is MORE resistant to the pressure inside.

You're using factory ammo. So nobody outside of Winchester knows what was inside that cartridge. And factory ammo may appear to be "the same" but when it comes from different lots, there are always going to be chances for some slight changes in production. They may change -any- part of what they used to create that load, and they may do it according to their own business needs.

What am I trying to say?
Simply: you can't truly compare the primers you see to anything unless you are comparing them to other rounds of ammo from the exact same production lot. Because if you compare them to:

--handloads
--some other factory ammo from a different manufacturer
--some other product from Winchester
--SAME product from Winchester but a different production lot
--or fired in a different rifle

...then all you truly know is that you simply don't have enough information to glean ANYTHING specific.

If you have a pierced or leaking primer, where pressure found it's way out, then you have a problem. If you just have primers that look different than other ammo you've shot, it really means so little that it almost truly means absolutely nothing.

When you have a bunch of once-fired brass from factory ammo all from the same production lot and all fired from the same firearm and THEN you have a bunch of different looking fired primers (and substantially different, I might add), then you've got some curious situation that should be investigated.
 
I think the reason this is happening is because the weight of the bullet (and consequently more powder). My gun already doesn't shoot heavier loads well. I looked at some of those Yugo 186.6 grain surplus casings I had left over and the catering appeared there, too.

Anyway, thanks for your help, denis. I plan on ordering a spam can of ammo today and my dad and I are going to start building a range soon. We're gonna use logs and dirt as a backstop along with the woods. It's just going to be a 100 yard range for me as I learn to shoot the Mosin better. Anyway, I'll keep you posted when I can. Thanks again.
 
nothing to worry about, if I recall correctly you also switched to a lighter firing pin spring after you switched off the winchester ammo so this should lesson the effect.
 
A lighter spring, yes. In hindsight, I probably shouldn't have worried about it. This ammo was shot a a few months ago, I need to shoot the rest of it to free up the brass. Anyway, thanks for your help everyone.
 
Just for record regarding your home-built range : the woods behind are in no way a backstop. You need to contain all fired rounds in your bullet trap.
 
In an ideal world, you'd KNOW for sure there's enough wood to positively stop rounds from penetrating to the embankment, upon the top of which cars travel?
Denis
 
In an ideal world, I wouldn't have to worry about it, but I'm confident that it won't go as far as to injure someone in their car. Thick pines and Oaks along with our backstop and the incline the range will be on will send the bullets straight into the backstop or in one of the trees (if it goes that far).
 
If I had the opportunity for a better range, I wouldnt be using it. Trust me, but the range near us's memebership was extremely too high, IMO.
 
Your confidence does not equate to actual safety. Either build a trap that will contain 100% of fired rounds or pay the dues at the local range. Your family does not have enough money to pay for hitting a person or a car, either.
 
Can anyone possibly be in the woods between your home built back drop and the embankment? You are responsible for every bullet coming out your gun.

BTW the cratering on the primer is mostly due to the oversized firing pin hole on the bolt face. Nothing to do with the spring being strong or weak. There is a way to fix it, but it is no worth doing on a cheap mosin. It is OK as it is. Don't shoot any hotter rounds. When you start hand loading, load it lighter. Worst case the primer may leak and you end up with one eye. It is highly unlikely unless you've done all the things that you shouldn't have.

-TL
 
"BTW the cratering on the primer is mostly due to the oversized firing pin hole on the bolt face"
That gets my vote especially considering the firearm involved.
 
Okay. The round WILL NOT, Providing I do NOT INTENTIONALLY AIM AT THEM, HIT A Car. Here Is a Verbal Diagram of the range.

Here is the bench. It is on top of a slight incline (Maybe 20*)
Next we have the Range, 100 Yards.
Then. The Backstop 2-3 Yards Long and 1 Yard High. A Large Dirt Pile with rocks and logs mixed in.
Then, we have the woods. Several Pines, a few oaks, lots of other trees and brush slight undulations in the terrain. maybe 15-20 yards of woods.
Then, the embankment. Its at a 70 degree angle going upward about 5 feet from the end of the woods all dirt.

As stated previously, unless I INTENDED to shoot someone, I couldnt.

tangolima, no one is going to be on our land without our permission, and if they are...well... It still wouldn't hit them.
 
All I can say is "You obviously haven't seen the results of bullets seeking their own path after hitting an object". Some night firing with tracers will make you say "How the heck did that bullet go that way?".
 
And as for the primers, I looked at some lighter load surplus and Tula 147 grains
and there were either no or very obscure craters that i couldn't see.
 
Status
Not open for further replies.
Back
Top