If you have a lathe, making a rim swaging tool can't be too hard - all you need is essentially a decently-sized steel block with a centered hole that will accept the case body, and a rim recess at the bottom spec'd just a bit thinner than whatever you need.
1. Insert case from the bottom and put on a hard steel surface,
2. then whack (hard) with a (large) hammer, and the rim is swaged. Sometimes you need to repeat the hammer treatment a few times...
3. remove case, insert new one and repeat.
I have just such a tool for converting 32-20 cases to .310 cadet. Works a treat! It is rather loud though...
Webley MKVI
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