Seconding this one. Looking at the furthest from camera case, my money it that there is play in the cylinder along the axis of the cylinder pin. That case being swollen, just above the rim means one thing, that the case has enough room to move back out of the cylinder while firing to allow that to happen. Overpressure i.e. hot loads may be contributing to an issue you wouldn’t observe with lighter loads. Have you played around using different ammo?
remotelove@lemmy.ca 3 days ago
I agree with the comments on this forum (www.thehighroad.org/index.php?threads/mushrooming…) that the cylinder could have a machining defect. (Basically a headspace issue, also but kinda not. The cartridges are sitting too deep in the cylinder itself.)
If there is room for the brass to get pushed back far enough for it to mushroom out, something is seriously wrong.
My first thought was excessive chamber pressure, but the bulging would be much worse around the rim itself if that were the case.
The bullet and the brass get pushed in opposite directions and if the brass can move, it will move before it deforms. If it deforms, it’ll deform at the weakest spot first.
Doofytoe@sh.itjust.works 2 days ago
shalafi@lemmy.world 2 days ago
All ammo, all cylinders. Taking it out in a bit and holding the cylinder tight against the gun when I fire. Bet money that works, not sure where to go from there.
Doofytoe@sh.itjust.works 1 day ago
There’s two things that could get it acting right that I can think of: Replace the cylinder (expensive, may not work but might) Shim it i.e. find a washer with internal diameter of cylinder pin or smaller and rut it out to the right diameter, then file it down to the width that takes the play out ( couple issues with this, one it’ll increase the flash gap i.e. bigger halos, reduced velocity and increased leading, two potential annealing of the makeshift shim with the fram of the gun) Let us know how it goes
shalafi@lemmy.world 2 days ago
play in the cylinder along the axis of the cylinder pin
Got me in the zone! Testing today and the cylinder pin wasn’t seating tight. Tried to tighten the release button, already tight, seemed good for a minute.
Fired 6 rounds, but it got sticky. Same issue, but not as bad. Too tired to mess with it more tonight, but the cylinder is indeed moving forward on the cylinder pin axis.
You are now my rubber duck.
MuttMutt@lemmy.world 3 days ago
This was my initial thinking as well. Could also be something loose in the cylinder connection that is allowing it to move and shift around side to side just enough to allow the brass to deform.