pierced primer

[sako2]

I took my finnwolf to the range today with some test loads. I used a 150gn hornady sst and varget for powder remington 9 1/2 primer. 40gns was fine 40.5gns pierced the primer. Came home pulled a round apart weighted the bullet and charge everything was good. C.o.l was right. Measured the fired cases and they measure the same so i don't think i hurt the gun. Scratching my head as to way it pierced the primer.

 

[Guy Miner]

Hmm. Good question.

 

[RL338]

Pierced primers for me were from excessive firing pin clearance. It showed up with I switched to SRP brass.

 

[clearwater]

i had a burr on the firing pin that caused that. took a ceramic knife sharpening hone to it

 

[sako2]

These were lr 3 of 4 were fine

 

[TackDriver284]

These were lr 3 of 4 were fine

What caliber is this?

 

[wvbuckbuster]

Two years ago when I was working up loads for the 270win barrel that Douglas put on I had a primer to pierce and it was good bit under max load. Turned out to be a bad piece of brass FC if that makes any difference. Scrapped that lot (was kind of old) no more problems.

 

[sako2]

Tackdriver it's a 308 lever action. I'm going to measure my case length again I trimmed them to max length if I remember right. I've been trimming my brass to max length to help with carbon build up.

 

[RL338]

40grs of Varget is a pretty soft load for a 308 and 150s. I’ve never used Remington primers perhaps yours had some with a thin cup.

 

[TackDriver284]

Tackdriver it's a 308 lever action. I'm going to measure my case length again I trimmed them to max length if I remember right. I've been trimming my brass to max length to help with carbon build up.

Nosler reloading data shows that 40-40.5 grains of Varget is a very soft load for 308 and 150's. Might want to swap primers and use CCI primers, its a harder cup and see if it solves the issues with primer piercing. Keep us posted.

 

[sako2]

Did some more measuring my case length is good. Measured my c.o.l. and i'm .185 off the lands.

 

[superdrupal]

I would rule out excessive headspacing first. Perhaps you're pushing the shoulder too far and it's causing more force back into the firing pin. Following that I would look at seating depth. While you've seated to book COAL perhaps with that chamber and bullet combination it's quite jammed into the rifling, which may cause a pressure spike. It might be worth checking CBTO instead as it would give you a more accurate measurement than overall length.

 

[sako2]

Sized the case to bumped the shoulder back .002. And measured cbto . I'm limited on c.o.l because it's a box clip.

 

[superdrupal]

Sized the case to bumped the shoulder back .002. And measured cbto . I'm limited on c.o.l because it's a box clip.

Hmm, maybe use check weights to confirm the accuracy of your powder scale. Assuming that's good, I would swap out components. Primer first then perhaps brass.

If you're wanting to use that bullet for hunting, I'd buy a box of factory Hornady ammo and compare outcomes and velocities.

 

[300WSM]

Letd go into inspector gadget mode.
Go go gadget picture.
Can we see a picture of it?

Go go gadget primer...
from the 40.0 grain case?

How does it look? The one that didn't get pierced. If it looks like a normal struck primer the problem is NOT your firing pin.

Could it be possible....
The pieced primer wasn't fully seated?
Not questioning your reloading prowess but oversights happen all the time. To all of us.

Several other possibilities as well....

And the answer is probably pretty simple.
Unless your other fired primers look odd you can rule out firing pin.

After that case differences between the pieced one and others.

Let us know

 

[sako2]

Don't have any pictures. I had shot a box of Norma whitetail ammo in gun last fall. All other primers look fine. All the brass measures the same. I do recall the lever cracking open when i fired the shot.

 

[Joec7651]

Is it an ongoing occurrence, or just the one time?

 

[sako2]

This was the 1st time. I never had a primer pierce until this 1. I believe i found why it happened. I screwed up when i sized the cases. They were not fired in my gun i got them when i purchased a guy's entire reloading supplies. He used them in his match rifle. I set the die up to do a full resizing. When i measured them against the brass fired in my gun I got a difference of .013. That's to the datum on the shoulder. I reset my die up to bump the shoulder back on the brass fired in my gun ..002. So yes i caused excessive headspace.

 

[300WSM]

This was the 1st time. I never had a primer pierce until this 1. I believe i found why it happened. I screwed up when i sized the cases. They were not fired in my gun i got them when i purchased a guy's entire reloading supplies. He used them in his match rifle. I set the die up to do a full resizing. When i measured them against the brass fired in my gun I got a difference of .013. That's to the datum on the shoulder. I reset my die up to bump the shoulder back on the brass fired in my gun ..002. So yes i caused excessive headspace.

You said you FL sized them but then said you compared to your fired cases from your gun and adjusted the die to do a shoulder bump.

Or...Are you saying you only sized one case and measured then changed the die.

I'm only asking as many people read this forum and want you to be as clear as possible. It can always help someone. (Unless I am not reading you correctly)