Pierced primers

[Tempest]

Greetings:

Some background. This is a custom Savage FTR rifle. Been shooting this combination for 4 years. It's a proven load many people shoot, so I don't feel its a over pressure situation and never had this problem before. 1st time shooting this year, I'm getting primers that look like this below. The only changes I made over winter were, pulled the barrel to thread for a tuner. Changed firing pin spring because it was getting old.

I'm thinking too much firing pin protrusion?

https://static.wixstatic.com/media/008a74_58317586bda94efe900a594edc01a4ee~mv2.jpg/v1/fill/w_750,h_423,al_c,q_80,usm_0.66_1.00_0.01/Snap_004.webp

https://static.wixstatic.com/media/008a74_5419b1690b044ebe9a2a156e7d7c1783~mv2.jpg/v1/fill/w_750,h_423,al_c,q_80,usm_0.66_1.00_0.01/Snap_006.webp

[Stumpkiller]

Primer is not flattened, so I believe your pin protrusion assessment is correct. Assuming no other signs of over-pressure.

[celltech]

So just what did you set the protrusion to?

[Tempest]

I thought it was .050" but checked yesterday and was .061".

One other thing. With the scarcity of primers I did go from BR4 to 400.

[celltech]

I thought it was .050" but checked yesterday and was .061".

Make it more like .035"...

[GrenGuy]

^^^ THIS. You have 2 issues, maybe 3. Too much firing pin protrusion, and CCI 400 are very thin. While Your at it, make sure the firing pin tip has a rounded radius, not a point. The ultimate fix is have the firing pin hole bushed. All this info can be found on this site with a search.

[Evlshnngns]

Cci400 is the only primer I have ever pierced. A br4 is a thick cup cci400. Cci 450 is thick cup with hotter compound.
My peirced 400 load shot great, br4 fixed the problem.

[Tempest]

Wish I could go back to BR4's. They are non existent around here.

[Nor Cal Mikie]

Here I go again but, the first thing I think of? Has the brass been fire formed to that chamber? Too short and being pushed forward on firing, goes BANG and gets slammed back onto the bolt face and firing pin (being too long) punches (craters) the primer? Just thinking out loud.

[Robinhood]

Your firing pin protrusion is too long but that may not the problem. Once the firing pin depresses the prime, probably less than <.020" it cannot move any farther forward. Meaning the excess protrusion will end up being a gap between the firing pin stop and the nose of the bolt head.


NorCalMikie hit on one potential problem. The others are the potential for the firing pin hole to be oversized, or the radius on the firing pin extending beyond a 32nd below the tip(grenguy). Then there is the primer cup and high pressure. It is possible it is a combination of these latter issues.

[Tempest]

Yes fire formed brass. 4 years of matches. Thousands of rounds. Never had problem until firing pin spring changed and BR4 to CCI 400.

Going to shorten protrusion length and see if I can find some BR4's.

[Texas10]

The cratering seen on the primer close up photo says it all. You've got the combination of high pressure, a thinner primer cup material and too much clearance between the firing pin and hole. This allows the primer cup to flow back up into the firing pin hole enough that it works just like blanking die, shearing off the primer cup material. Hence why it's called "blanking" a primer and a recipe for trigger damage too.

If you can't find BR-4's, have the bolt head bushed. In addition to curing the blanking issue, you'll get better ignition too. Been there, done that.

[Tempest]

If pressure was high I would expect to have seen this over the years. 4 years of shooting this combination in 90 deg temps and not seen this until I changed spring and also primer.

It's a load probably 90% of the FTR we shoot with use.

[Nor Cal Mikie]

Out of all on my Savage rigs, (I think 6 now?) all using CCI BR primers with no issues EVER, and not one of my firing pins have been bushed!!
Correct the pin issue and go from there.

[Evlshnngns]

If you cant find br4's drop down in powder a touch and work up with cci450s.

[bigedp51]

CHOOSING THE RIGHT PRIMER - A PRIMER ON PRIMERS
http://www.sksboards.com/smf/index.php?topic=56422.0

Small Rifle Standard

CCI 400 -thin .020" cup, not recommended for AR15 use by CCI/Speer. Good for .22 Hornet, .30 Carbine. See Note 1 at the bottom of the page

NOTE 1: According to Speer/CCI Technical Services - Both the CCI 550 Small Pistol Magnum and CCI 400 Small Rifle primers are identical in size. Both primers use the same cup metal and share the same cup thickness. Both primers use the same primer compound formula and same amount of primer compound. They can be used interchangeably.


https://i.imgur.com/QJM65zp.png

[tomme boy]

CHOOSING THE RIGHT PRIMER - A PRIMER ON PRIMERSkooi
http://www.sksboards.com/smf/index.php?topic=56422.0

Small Rifle Standard

CCI 400 -thin .020" cup, not recommended for AR15 use by CCI/Speer. Good for .22 Hornet, .30 Carbine. See Note 1 at the bottom of the page

NOTE 1: According to Speer/CCI Technical Services - Both the CCI 550 Small Pistol Magnum and CCI 400 Small Rifle primers are identical in size. Both primers use the same cup metal and share the same cup thickness. Both primers use the same primer compound formula and same amount of primer compound. They can be used interchangeably.


https://i.imgur.com/QJM65zp.png
I wish everyone would stop spreading this photo. CCI changed the primer on the spm and is not the same anymore. And your firing pin spring is causing this. Put your old one in and try it again. If it fixes it then your new spring has less pressure than the old one

[Texas10]

I have written to CCI concerning this apparent discrepancy and will post their response.

[243winxb]

https://forum.accurateshooter.com/threads/why-less-powder-cratered.4033028/ CCI 400 primers most likely the problem.

[Tempest]

Response to my initial post:

Did match Sat with CCI 450 primers. Same load, did not even back down powder for magnum primer as it was cool. Problem went away.