case mouth peen

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mdeland
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Joined: Mon Nov 20, 2006 1:47 pm

case mouth peen

Post by mdeland »

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.
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Lumpy Grits
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Re: case mouth peen

Post by Lumpy Grits »

It happens from to high of RPM of the tumbler.
I have never had the peen issue.
Gary
"Hav'n you along, is like loose'n two good men"
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Lumpy Grits
Posts: 7673
Joined: Tue Jan 28, 2003 7:58 pm
Location: Springfield, Missouri-U.S.A. Earth

Re: case mouth peen

Post by Lumpy Grits »

It happens from to high of RPM of the tumbler.
I have never had the peen issue.
Gary
"Hav'n you along, is like loose'n two good men"
mdeland
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Joined: Mon Nov 20, 2006 1:47 pm

Re: case mouth peen

Post by mdeland »

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.
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Lumpy Grits
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Location: Springfield, Missouri-U.S.A. Earth

Re: case mouth peen

Post by Lumpy Grits »

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
"Hav'n you along, is like loose'n two good men"
Randy Bohannon
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Location: Buffalo WY

Re: case mouth peen

Post by Randy Bohannon »

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.
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