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Breech Face erosion already


PaulW

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Picked up a new Trubor 38 super and after test firing, shooting the match Saturday, and some steel practice Sunday I noticed that I am already getting some bad breech face erosion. This after 300 major pf and 300 minor pf loads. Is this normal. I have owned my share of open guns and never recall seeing this happen so fast on an open gun.

Edited by PaulW
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My guess would be the minor loads are what did it and they did not have enough pressure to seal the primer since you were using mag and rifle primers and the gas leaked out and did that which would explain the circle about the size of a primer

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If it has a crack, I'd suspect weak metal.

Before seeing that, I was going to ask if you were running magnum or rifle primers with the minor loads. I have a theory that sometimes a low power load won't have enough strength to properly force the primer cup to seal against the primer pocket...letting gases jet by. It's only a theory, based on just my one gun with an eroded breach face.

[edit to add: wow, lots of responses sneaked in while I went for coffee before posting]

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shouldn't matter with the DE-swager running, if the primer pockets are not swaged, then the de-swager won't do anything...

Minor loads with rifle primers is the problem. There isn't enough pressure to seal the primer cups to the pocket walls, because rifle primers have harder cups than pistol primers.

jmho... :)

jj

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speechless. I would think a bad slide. That is just nasty. And it isn't from using rifle primers either, I use small rifle CCI's in my STI and there is no signs of this happening at all. Is your cartridge headspacing correctly?

Edited by Got Juice?
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Only major pf loads were used with the rifle primers. Most we're small pistol magnum primers, not sure how much different those are to small rifle primers?

Good news is I am sending back to STI. I have a whole list of things for them to check fix. One thing I noticed tonight is the barrel timing appears to be off, at least in one area. With just the slide/barrel on the frame, slide stop inserted but hanging down, if I press the comp against the bench in theory the barrel should stop against the frame and no pressure should be on the slide stop. Not this one, it is against the slide stop and I cannot pull out or rotate the slide stop at all. It has a #4 link in it so I tried a #5 link to allow the barrel to travel a little more rearward. Bingo that took the pressure off the slide stop. Now I realize that is just one small test to a properly timed barrel but that one is pretty important, IMO.

Anyways.....hopefully STI can turn it around pretty quick and fix all the things that are wrong. I also am going to use a different powder and new brass, and only major pf loads for the first thousand or so rounds. I was using Autocomp at 8.1 gr with a 115 gr MGJHP. But after reading up on it that may have contributed, IDK. This is only like my 7th or 8th open gun, just have never seen such a thing happen.

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