Punctured Primers DPMS Panther

[TheDuke]

Ive a DPMS Panther that has started 'puncturing' primers. I first noticed this at about 450 rounds..Since there were no obvious pressure signs other than the little hole in the primer, I changed primer brands...tried all the major brands, mag, reg, and mil...So that isnt it...Replaced firing pin x 2, checked headspace,made sure all my brass was sorted correctly..I was shooting 40 1/2 H4895 with 175 SMK into 1/2inch providing I did my part....A little hot maybe at chrono 2640-60 fps

The good folks at Sierra sez may be a hot lot of powder, so backed off to 38 gr..This doesnt puncture the primers, but doesnt shoot as well as the 40 1/2...I called DPMS and got some double talk that ended in "send it back to us."

So I try factory loads...Georgia Arms 168g no problem...Fed 175 MK no problem but I cant afford to shoot too many...Tried some Sellier and Belliot 175match although not as good as my reloads, quite OK for accuracy...Then I picked up the brass..Yep..popped evey one of them...back to square one..

Anyone had a similar problem with a solution??? Im about to replace the bolt head as Im thinking the firing pin hole has enlarged or too big to begin with...

I grasping at straws, but I stuck in a Chip McCormic drop in trigger before I found out that DPMS doesnt recommend them for the Panther...Cant see how this may effect the primer or could it????

I dont know, but thought I throw it out and maybe someone has had this problem before me or has some ideas..Sorry to be so long winded...Thanks

 

[Blackfork]

Erosion in the bolt face?

When they start piercing the tip of the firing pin erodes- which makes them MORE likely to erode more and pierce more, but also the hole that the tip of the firing pin protrudes through the bolt face also erodes. Erosion in that area can make even a new pin come through more, leading to pierced primers and starting a snowball effect. Might take a very close look at that area with a magnifier. It's got a little shoulder cut and there is a gauge to measure how much a firing pin extrudes through the bolt face surface to pierce the primer.

 

[Jim K]

Check the firing pin, but the real cause of "pierced" primers is not a sharp firing pin, too much protrusion, or a hot load but rather a light hammer/firing pin blow. (In a rifle like the AR-15, it can also indicate a bolt not closing fully so there is insufficient firing pin protrusion.)

What happens is that when the firing pin hits the primer, it must not only set off the primer but must also support the indented part of the primer against the internal pressure ignition generates. If it does not do that, the primer metal pushes the firing pin back and then flows back into the firing pin hole in the bolt. That "tit" is then cut off when the bolt opens, leaving a hole in the primer and a tiny disc inside the bolt; if enough discs build up, they will eventually cause misfires.

Jim

 

[rcmodel]

Checked your barrel for copper fouling?

If severe enough, it could cause high-pressure.

Get some good copper solvent & see what comes out.

rc

 

[TheDuke]

"Check the firing pin, but the real cause of "pierced" primers is not a sharp firing pin, too much protrusion, or a hot load but rather a light hammer/firing pin blow.

AH HA!!!!!!! (Huge Brilliant Flash as the light bulb clicks on...)I think this may quite possibly be the answer...Ive both a JP and CMMG trigger in my parts box .... Either should allow me to play around with the hammer spring as opposed to the drop in Chippie....

Jim, I think you nailed it !!!..The nibbs have caused misfires and Ive had to clean out the firing pin channel...several times...Your description is exactly what is happening with my rifle. Time for a different trigger and hammer spring.

Thanke, Thanke, Thanke!!!!!!!!!..Soon as I can get around to do a little range testing I will report back...

 

[TheDuke]

After action report! Jim, you got it...Changed the rather frail Chip McC and replaced with CMMG..Fired off a few rounds and not a pierced primer in the bunch!!! Im not happy with the trigger pull yet...Prob replace the hammer spring with a Wolff reduced power tomorrow and see what happens..I really dont see a lot of difference between the CMMG triggers and the JP Enterprise...The JP does have a reduced power spring...

Got to say, the Chip had a wonderful pull, but may have to settle for something a little heavier...Think I will post something to see what other folks are using..Thanks again for the good advise.