Hole in primer after firing (UPDATE 9/18/11)

[Izrua]

UPDATE(9/18/11): Readjusted the headspace (tightened). Fired 13 rounds (factory ammo, Norma brand, 6mm Norma BR).
11 rounds have severe cratering on the primer, 2 rounds have a pierced primer.

The 4th round and the 9th round are pierced. The piercing looks different than the previous occurrences, you can see what looks like a pin strike on the 'bar' inside the case.


OLD: I have a rig in 6mm norma BR, the firing pin is going all the way through the primer, creating a perfect round hole. There is no indications of pressure issues, there is no cratering or cracking on the brass or the rest of the primer.

The ammo is factory. Savage target action.

 

[NorCalMikie]

Hole in primer after firing

Only one or a bunch of primers? If the firing pin has "never" been adjusted and is still at the factory specs, my guess is that the case is too short (headspace) for that chamber and when the round was fired it got slammed back against the pin?
If you've got a bunch of "pierced" primers, start checking how far the firing pin sticks out of the bolt.
Reload the cases and see if you still have the problem after the cases are fireformed to that chamber.

 

[Izrua]

Hole in primer after firing

Only shot two rounds, both were punctured. I'll reset the headspace again. Not exactly sure now to check the how far the pin is coming out.

 

[NorCalMikie]

Hole in primer after firing

What brand of rifle is it?

 

[J Fogg]

Hole in primer after firing

Had that happen once, check the tip of the firing pin I believe it should have a slight flat on the tip and should be rounded especially the edges. The edges of mine were straight and would do the same thing, stoning to a rounded contour fixed it, several hundred rounds of the same load and no problems.
Joe

 

[Izrua]

Hole in primer after firing

What brand of rifle is it?

savage target action

 

[Izrua]

Hole in primer after firing

Had that happen once, check the tip of the firing pin I believe it should have a slight flat on the tip and should be rounded especially the edges. The edges of mine were straight and would do the same thing, stoning to a rounded contour fixed it, several hundred rounds of the same load and no problems.
Joe

Looking at the pin now, the tip is rounded as it should be.

 

[NorCalMikie]

Hole in primer after firing

If you reload, load those cases that have been fireformed and see if it makes a difference. If the case will fit back in the chamber and the bolt closes without too much force. stuff a primer in it and load it up. Load the OAL to a jam. That will keep the case back against the bolt head.
The Savage firing pin is set at the factory and my thinking is the fired test rounds would have showed any problems but mistakes happen.
Firing pin protrusion should be .052 to .060.
I'am still thinking the cases "may" have been too short for your chamber. When fired in the loose chamber the brass gets pushed back to the bolt head and sometimes the primer gets pushed out of the pocket. That's when the primer gets pierced.
And a tighter headspace isn't a bad thing. Means you won't have to push the shoulder back any more than needed. The less you work your brass, the longer it will last.

 

[Izrua]

Hole in primer after firing

Thank you both for the info, much appreciated. I'll go back out when i have a day off and see if its fixed.

 

[bozo699]

Hole in primer after firing

Izrua,
Welcome to the forum, I as well believe you have a head space problem, if I had a suggestion for you I would just cut and paste NorCalMikie's post as I believe he is spot on.
Wayne.

 

[watercam]

Hole in primer after firing

I have an interest in this thread as I just had one pierced primer (out of 450 rounds) in my Palma rifle during a match. It is a Win. 70 action with .070" pin projection. Just one does not worry me too much unless it becomes a regular occurrence. No gas escaped, the round went where I aim (more or less). Any thoughts are appreciated.
Mike T.

 

[bozo699]

Hole in primer after firing

watercam,
Again Mike is right, .060 is on the high side of the norm. you may have not had the primer completely seated but I would set it at .060 where it should be.
Wayne.

 

[NorCalMikie]

Hole in primer after firing

Mike: One pierced primer out of 450 rounds fired isn't anything to worry about. I've had a few and figure it's because the case shoulder got pushed back and when the round got fired, the primer was pushed out of the pocket enough to let the firing pin punch a hole in it. And on a few on mine, they wouldn't fire because the firing pin pushed the case forward in the chamber and the pin couldn't hit the primer hard enough.
First thought is a bad batch of primers? It usually turns out to be a short case. (just when you think you've got everything figured out :) The more we do these things, the more we don't know as much as we think we know.
And in my case, when my round wouldn't go off, I didn't bother to measure the case. Just pulled the bullet, reloaded the round , stuffed it back in the box for the next time.
And out of about 10,000 primers, I've never had a bad one so I rule that out.
It usually comes down to not doing something the way it should have been done and when something goes wrong or not the way we think it should have, we blame it on something else. We're not perfect or at least I'am not. We're suppose to learn from out mistakes?
There's guys on here that know "a LOT" more about this stuff then I ever will. I just try to remember what I did wrong and not do that anymore. ;D

 

[spclark]

Hole in primer after firing

Some primer brands are more prone to "blanking" with reasonable loads than others though of course the condition of your firing pin's tip and other metrics play a part too. I'm not familiar with Savage specs but 0.060" fp protrusion is what all my rifles are set for.

The one time I've had problems with piercing were with one particular AR spacegun upper & I was using original Murom Plant (since Russian/Wolf/PMC) KVB-223 primers & they're known to have rather thin cups. Switched to BR-4 or later the Wolf KVB-223 REM product (magnum cup, normal SR charge) & no more problems.

 

[huffmanite]

Hole in primer after firing

Have a .223 Savage Edge/Axis rifle.....probably a couple of hundred rounds down range with it. Past weekend, shot 20 rounds in it and my reloads were with Fiocchi SR primers. When resizing the brass the following day, found 4 of my 20 reloads had pierced primers, which puzzled me. I've not used many of these Fiocchi primers in my .223, maybe 50 or so, but none had been pierced before. I was nowhere near max loads for my .223.

 

[NorCalMikie]

Hole in primer after firing

4 out of 20 primers pierced on "my" reloads? First thought? Oversized brass. Short case (shoulder being pushed back too far) allowing the primer to be pushed out of the pocket, firing pin punching the hole as it's being fired. Check headspace on brass.
If the fired case will fit back in the chamber and no excess force is needed to close the bolt, reprime, stuff a bullet and powder in the case and go shooting. Report back your findings.

 

[fguffey]

Hole in primer after firing

Head space? all ways it is head space, there is one forum that has one answer for ever question, purchase a comparator from so and so.

Head space by any description or definition does not hang me up, I use datums.

If I have a firing pin that punches a hole in a primer I check the firing pin spring. It is impossible to convince someone the spring off sets the effect of pressure in the chamber, because, after all, the pressure can be 55,000psi++ but that is what it does after crushing the primer.

If the primer has a dent in the primer after firing, the pressure forces the primer to conform to the protruding primer, if the spring is too week the pressure inside the case/primer pushes the firing pin back and THEN! a round hole appears.

And if allowed to continue, the hot, high pressure, metal cutting gas will cut the bolt face and make the hole in the bolt face larger, THEN! primers with craters.

F. Guffey

 

[fguffey]

Hole in primer after firing

Then there is the head space and primers, again, look at the bolt face, hot, high pressure, metal cutting gas escaping around the edge of the primer will cut the bolt face, first it appears as a black ring, and then? A ring is cut in the face of the bolt in the shape of the primer.

Then there is the flawed illustration/demonstration with the sequence of events when the trigger is pulled, the firing pin hits the primer and the bullet, case, powder and primer accelerate to a speed equal to the speed of the firing pin and then the shoulder of the case hits the shoulder of the chamber....? Think about that, my primers are crushed before the case, bullet and powder know their little buddy, the primer, has been hit, as I said 'flawed', provoking someone to think is not easy.

F. Guffey

 

[fguffey]

Hole in primer after firing

Forgive, he calls his comparator a head space gage. ???



F. Guffey

 

[bozo699]

Hole in primer after firing

F.Guffey,
Are you carrying on a conversation by yourself?
Wayne.