Shooters who convert factory actions to run 6BRs, 6PPCs or other high-pressure cartridges should consider having the firing pin bushed. These modern cartridges like to run at high pressures. When running stout loads, you can get cratering caused by primer flow around the firing pin hole in the bolt face. The reason is a little complicated, but basically the larger the hole, the less hydraulic pressure is required to crater the primer. A limited amount of cratering is normally not a big issue, but you can reduce the problem significantly by having a smith fit a bushing in the firing pin hole. In addition to reduced cratering, bushing the firing pin often produces more consistent ignition.
This is a highly recommended procedure that our editors have had done to their own rifles. Greg Tannel (Gre-Tan Rifles) is an expert at this procedure, and his turnaround time is fast — usually 2-3 days (shop time). Current price for a bushing job, which includes turning the firing pin to .062″, is $64.00 including return shipping. (Price subject to change.)
If you have a factory rifle, a bushed firing pin is the way to go if you are shooting the high-pressure cartridges such as 6PPC, 6BR, 6-6.5×47 and 6.5×47. This is one of the most cost-effective and beneficial upgrades you can do to your factory rifle.
I had a remington 700p in .223 that I converted to a 6br. after I opened up the bolt face the firing pin hole was a little loose. I was having issues with primers actually getting cut around the firing pin hole and jamming the firing pin during a match. I sent the bolt out to greg and he fixed it right up. ceramic coated the bolt too. highly recommended.
Comment by Matt Doherty — July 4, 2009 @ 8 am
I have read a lot about bushing the firing pin. While I am not saying “don’t do it” if we do do this, are we not just hiding the pressure signs? Think about it – we use primer cratering to know if a load is getting too hot for the gun, then we bush the firing pin and now we can run hotter loads? To me that is like saying the car has a rattle above 70MPH, so if you are driving 75 turn up the radio so you can’t hear the rattle.
Comment by Neil LeJeune — July 7, 2009 @ 6 am
Using primer cratering as a pressure indicator is not recomended because of the great variation of primer metal hardness.
A better way is to measure the diameter of the head of the case before and after firing. Use a good micrometer for this. If the expansion after firing is over .001″ the load is too hot for that combination.
Be aware that different lots and makes of brass have different characteristics and may react differently to pressures.
Mixing different makes of brass is not a good idea.
Weigh your brass and try to keep it in lots of +/- 5 grains.
Comment by Pat C. — November 22, 2009 @ 4 pm