Ok, so a friend and I are having similar issues with pierced primers and excessive primer cratering/flow in 6mmBRs built on Savage model 11 Actions.

First a little history. I built my wife a BR to shoot in our monthly local matches. Build went together fine broke in the barrel and found a sweet shooting load with 30.3 grains of Varget under a Berger 105gr VLD. Primers showed a bit of cratering with that load but pockets remained good and tight and the gun grouped in the .2's when she did her part. Fast forward a couple months and it was now time to order some more Varget because we were out. Had a match last month and the last two shots of the string pierced primers. We only fire ten round strings. I figured it was due to having a different lot of Varget and it was running a bit hotter than the last batch which I have read is a common problem with Varget. So I went down to 29 grains and was going to work my way back up to a good node and every primer was pierced. There were no other signs or feeling of excess pressure with easy case extraction and primer pockets remain good and tight. I did some research on the FAQ page here and find that the optimum firing pin protrusion is .037". Mine was set at .056" which from what I gather is factory spec. I followed the tutorial and fixed my protrusion so that it is now .037" and while I still have some primer flows I have have not had a pierced primer and my groups are great at 29 grains of H4895. I decided to try some H4895 to rule out Varget as my problem and I am glad I switched.

Now while the wife's rifle was shooting well I had a friend ask if he could build a 6mmBR as well because he was so impressed with it. I said sure and we got all the required components ordered and assembled about two weeks later. He went ahead and purchased a brand new Savage model 11 hunter xp with bottom bolt release in .243 for his donor action. We screwed on and head spaced the McGowen 26" varmint contour barrel, mounted a scope and loaded some rounds with AA4064 for break in. First three shots at 28 grains pierced primers. We checked his protrusion and it was set at the factory spec .055" problem is with the new bolt style of the new action there is no way to adjust the protrusion like there is on the older bolt. He has since tried moving to Benchmark powder and using start loads with one of every three piercing primers and the others showing excessive flow. My question is this. Is there a problem with our bolt heads firing pin holes being over sized allowing the excessive primer flow and if so, how do I fix it? Is there a different bolt head we should be using because we are shooting a cartridge with a small primer hole in a .473 sized head? Sorry for the excessive post but all help will be appreciated. Thank you.


We are both running the same components:
Norma Brass
CCI Small rifle primers No. 400


Here is some pictures of his cases he sent me last night.