Shiloh Rifle Forums

I was trimming some 38-70 cases today and got to thinking on the case mouth peen that some folks report. I'm wondering if there is a connection to power chamfering tools and mouth peen.
I check my brass routinely and have never seen it occur inside or out and wonder if it is because of hand chamfering as opposed to power chamfer that may produce a thinner case mouth perimeter that could be more susceptible to peen .
The other thought was perhaps over annealing.

It happens from to high of RPM of the tumbler.
I have never had the peen issue.
Gary

It happens from to high of RPM of the tumbler.
I have never had the peen issue.
Gary

The only trouble I have with that idea Gary is I use a high speed Thumblers tumbler with Dave Mauer's ceramic angle cut media and soap for all my case cleaning. The cases and media are just barely covered with warm water then a cap full of the soap and tumble for 1.5 hours.

I use the low speed version with Dave's media.
Load pretty much as you do. Run for 1 1/2-2 hours.
Never have I had any casemouth damage and the cases come out looking like new, inside and out including primer pocket.
Gary

I too use same set up as mdeland for my BPCR brass only difference is my tumbler is the slower ‘B’ model. I also VLD chamfer case mouths after annealing/trimming when new very lightly just enough to get the desired angle not to a knife edge. I have yet to notice any peening PP bullets fit as always.