I shot about 20 rounds and got some loose primers in 8 of them. So I quit shooting them.
October 17, 2004, 07:05 PM
If you look at most ceterfire rifles after they've been used for a while this circle around the firing pin oriface is quite common.
October 17, 2004, 09:08 PM
Wil is right, I've seen lots of misurps such as M98 Mausers that have quite a groove.
October 18, 2004, 01:24 PM
The 98 Mausers have had corrosive primers leak, which later etched the steel.
That is allot worse than the carbon stains shown above.
October 18, 2004, 02:05 PM
If the gas came back, it could have gone into the firing pin hole, too. I had a bolt freeze from this once, but yours may not be that extreme, especially if the primer didn't burst. If it did, you'll have copper and other chemicals bonding the firing pin to the firing pin spring. This will have to be cleaned out. The carbon stain on the bolt face shouldn't be an issue, however.
October 18, 2004, 02:34 PM
I sure appreciate all of the replies.
I took the rifle apart and inspected everything. That etch in the breech face is probably .001 to .0015 deep.
The firing pin looks fine. All of the parts work smoothly. The action does not bind and opens and locks securely.
I also figured out what I had done. I thought in an earlier post that I had simply overloaded the cartridges and then fired them when it was too warm outside. The same load worked fine in the mountains at about 30 degrees.
But what I figured out last night is that I had let the cartridge OAL be too long and the bullet was touching the lands. Big pressure spike.
I loaded some new rounds down from the hot ones but I also grabbed the remaining hot rounds and adjusted the length down. Took a stoney point tool and measured the oal to get the bullet on the lands and then backed off five thousands.
The brass that was used to cause the etching is all pretty well trashed and will not be used again. Five of the shells would not fit in the shell holder! A couple had miniscule splits at the neck. I will keep them as a reminder to pay more attention!
I am going deer hunting this weekend, hopefully the hotter rounds will work fine now that they are of the correct length. I will get it sighted in this week and decide what to do from there.
October 18, 2004, 03:11 PM
Here is some .308 brass shot in my .243:
All three were the same load, but I now believe differed in copper fouling in the throat.
Any extractor groove growth is too close to the primer falling out.
I reduce the load by 6% from the threshold of extractor groove growth, and the loads look much like the loads in better load books.
A society that teaches evolution as fact will breed a generation of atheists that will destroy the society. It is Darwinian.
October 18, 2004, 04:06 PM
Are you saying the copper fouling in the throat was causing the fouling to touch the bullet and cause the pressure that made this happen??
That one on the right is unbeleiveable! I have never seen a primer flowed like that! No other damage to the gun??
October 18, 2004, 05:40 PM
They were all three in a row 40 gr IMR4895, 100 gr, [~60kpsi, very high, but not crazy] with very tight chambering.
For years it was bullet pinch, but now I realize the cheap Addams and Bennet barrel had button chatter and it fouled in three shots at the muzzle, and so it was fouling in the throat too.
Interenstinly, a guy from Hodgdon is quoted in Handloader magazine as sayinng that he never could get detonation in the lab, but did once outside the lab with a .243 with a very rough throat. Now I think he was mistaking copper for detonation and I was mistaking copper for pinched bullet.
That picture was downloaded from GlockTalk 2000 times until thier site went cheapo, and 6,000 times from the HIgh Road. The picture seems to talk to handloaders. I know when I saw the third round, I left he range and went home.
If you enjoyed reading about "Burned the Breech Face" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!