6BR Pierced Primers and Misfires

J

Joe

New member
Stolle Panda
Brand new never fired Lapua brass
New Bartlein 9 twist with 50 rounds through it.
6BR
CCI Primers (non-BR)
31.0 grains Varget (weighed)
107 grain Sierra Match King .015" into lands
22 degrees outside, 400 yard egg shoot

I had 6 misfires and 3 pierced primers!

Went to the range testing loads two times during this past week and fired approx 50 rounds through this brand new barrel and never had a single problem. Not a single misfire, no pierced primers, no signs of excessive pressure.

Loaded 35 rounds for the egg shoot and went to the shoot and had misfires and pierced primers.

Took the bolt/firing pin assembly apart at the shoot and did not notice anything wrong. No "specks" of dirt anywhere to be seen and no excessive oil on the firing pin.

I will note that these primers were out of a new package of 100. BUT......this package of 100 was out af a brick of 1,000 that I have been using and shooting for months so they are the same lot number.

Any ideas or suggestions?
Thanks
Joe Cowan
 
Joe, did you have any misfires before the first pierced primer? If not, you have some primer "blanks" in the bolt. Take the bolt apart and clean it out.

As to the primer piercing, or blanking, go to CCI450's. This will help immensely.

According to QuickLoad, if your COAL is 2.200" with the 107 SMK, you are generating about 76,900 psi pressure!! Just by backing off the COAL to 2.350" your pressure reduces to about 67,000 psi.

Of course, this is all theoretical and seating the bullet shallower would be would be dependent on freebore.
 
I had 2 misfires before the first pierced primer.
Took the bolt apart at the shoot and found nothing out of place. Took the bolt apart at home (under better conditions) and still found nothing.
 
I can understand headspace causing a misfire.
Would it also cause a pierced primer? How?
 
Joe, you say it was a brand new barrel. Is the action new also?
Check firing pin protrusion, should be about 0.055".
Check firing pin spring pressure, about 22-24 pounds.
Check firing pin penetration, should be about 0.020". (Measure the back of the firing pin when it is let down on an unloaded cartridge but on a seated and unfired primer, then pop the primer and measure again).
 
I was piercing primers on my Teddy at the nationals at Raton. George Kelbly was loading right behind me and I asked him about it. He told me to replace the firing pin spring. I did and the piercing stopped. George said that nobody believes the firing pin spring will cause pierced primers but it will.
 
MColeman said:
I was piercing primers on my Teddy at the nationals at Raton. George Kelbly was loading right behind me and I asked him about it. He told me to replace the firing pin spring. I did and the piercing stopped. George said that nobody believes the firing pin spring will cause pierced primers but it will.
Click to expand...
Mickey, George sells lots of springs that way. I have Carl or Tom to replace two of my four Panda springs each Super Shoot. That way my springs are not over two years old.
 
JerrySharrett said:
Mickey, George sells lots of springs that way. I have Carl or Tom to replace two of my four Panda springs each Super Shoot. That way my springs are not over two years old.
Click to expand...
Don't know if George was hustling $3 springs or not but it solved my problem. :)
 
MColeman said:
Don't know if George was hustling $3 springs or not but it solved my problem. :)
Click to expand...
They charged me $4,but then I'm not an FFL holder. I was just kidding about George peddling springs.

There is one thing (among many) George Kelbly knows very well and it is primer ignition and how to solve problems involving ignition.
 
Jerry Sharrett
I spoke to Jim Kelbly yesterday and ordered springs for both of my Panda actions.
He also mentioned to take the bolt apart and look for a cup from a pierced primer. There was one inside the bolt. I also polished the end of my firing pin because it had a very small hairline mark on it which, as I am told, could be the cause of pierced primers.

Another question.......How critical is the .055" firing pin protrusion?
My firing pin measures .043" while relaxed.
Could this be a problem?
Please e-mail me at cowanhaus@verizon.net
Thanks
 
Joe said:
Jerry Sharrett
I spoke to Jim Kelbly yesterday and ordered springs for both of my Panda actions.
He also mentioned to take the bolt apart and look for a cup from a pierced primer. There was one inside the bolt. I also polished the end of my firing pin because it had a very small hairline mark on it which, as I am told, could be the cause of pierced primers.

Another question.......How critical is the .055" firing pin protrusion?
My firing pin measures .043" while relaxed.
Could this be a problem?
Please e-mail me at cowanhaus@verizon.net
Thanks
Click to expand...

If excessive pressure is not the problem, or a poor fit of the pin tip to hole, then a weak firing pin spring usually is the problem with primer failure as described. There is a good chance the firing pin tip damage was caused by gas cutting when the primer failed. I think protrusion from 40 to 60 thou is acceptable.
 
Headspace

Back to headspace: if the case can move forward in the chamber even minutely this can cause misfires. This is often only seen with first time fired brass. The amount of protrusion of the firing pin can also be an issue as well as all of the other input already laid out above.
 
I've seen when guys are fireforming for the BRX or Dasher cases where the shoulders are moved forward that they will have more problems with blanked primers if they don't have a tight fit on their fireforming shoulder. With these cases, getting the fireforming shoulder located in the correct spot on the neck will go a long way to preventing blanked primers. As I've said before on other posts, if you are getting blanked primers, you need to figure out the problem and stop shooting it until you get it fixed or you are running a risk of damaging your trigger. When a primer blanks, gas is released inside the bolt, causing the cocking piece to be blown rearward and then dropping forward hard against the sear on the trigger. Do this enough or maybe even one time and you run the risk of breaking parts inside a BR trigger. One customer broke two Jewell's with blanked primers.

I'm not sure whether its a pressure thing or not, but a good fit on the cartridge case will help prevent blanked primers.
 
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