Comments on: Tannel Firing Pin Bushing Cures Primer Cratering

By: Jenson

Jenson — Wed, 14 Mar 2012 21:28:03 +0000

Seems to me that bushing the firing pin is just a modification to hide high pressure signs…

EDITOR: Not necessarily. With Accuracy Internationals for example (the actual AI action) there is a huge gap around the firing pin. This will allow cratering even at very moderate pressures well under the rated case max. I’ve seen that first-hand. Savages also have excess space around the firing pin. This can allow cratering with moderate loads. Again, I’ve seen it first-hand.

That said, if your gun does NOT crater at “practical max” loads, and then you keep going up cratering can, indeed be a sign of high pressure (along with flattening of primer, ejector mark, casehead expansion etc.). It’s smart to do so research on your loads and compare them to what other guys are shooting. Each gun/barrel is definitely different, but if you’re running a “book” load in the mid-pressure range yet getting cratering, it makes sense to bush the pin. You may be quite surprised at how effective this procedure is…

By: Stephen

Stephen — Wed, 14 Mar 2012 04:41:02 +0000

Is this a good idea for cases like the .308 or 7-08? I have a .473 RPSA that I was going to build a 338 Federal with for deer/hog hunting. This article has me thinking about a 6.5×47 instead, but it’s hard to make up for that much bullet diameter even though dead is dead. It’s the blood trail that bothers me, and .338 > .264.

By: Eric Kennard

Eric Kennard — Tue, 13 Mar 2012 02:57:30 +0000

Some of you are missing the point. The BR and 6.5×47 series of cartridges use a small rifle primer. The firing pins in most of the bolts listed have a large diameter firing pin. That is what causes the issues. I have done this on a BAT three lug action that should have been able to take all kinds of pressure but would in fact pierce primers with a warmer 6BR load. Once Greg turned the pin and bushed it, this problem disappeared. This modification is a must have for any one converting to these calibers.

By: Roy

Roy — Mon, 12 Mar 2012 23:19:33 +0000

A top shelf gunsmith that lives in a town named “Rifle”…..it simply does not get any better!!

Roy

By: Killshot

Killshot — Mon, 12 Mar 2012 22:45:50 +0000

I had Greg bush my firing pin hole as well as removing and filling in the ejector hole in the bolt face of my new Dasher build.

The fired primers and caseheads come out looking perfect, but………..short of using Quickload is there any other pressure indicator left to me besides loosened primer pockets?

Regardless, if you’re going to run hot-ish loads and want to keep your brass from being torn up, Gre-Tan is the choice.

By: Pat C.

Pat C. — Sun, 22 Nov 2009 23:58:31 +0000

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.

By: Neil LeJeune

Neil LeJeune — Tue, 07 Jul 2009 11:01:03 +0000

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 70 MPH, so if you are driving 75 turn up the radio so you can’t hear the rattle.

By: Matt Doherty

Matt Doherty — Sat, 04 Jul 2009 15:31:36 +0000

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.