I've had a problem similar to the OP's, when loading DEWC bullets in .38 Special. Wonderful bullets with small loads -- but sometimes hard to fit into the case, doing the same thing the OP showed in his pictures. Sometimes a thin shaving of lead goes down the outside of the case, other times the rim of the case is crushed downward.

A possible solution for the OP -- addressing the problem differently, but perhaps involving less effort -- might be to try a different brand of wadcutters (i.e., sell the ones on hand and replace them). he OP mentioned some of the bullets he is using are .359 at their base -- whereas many manufacturers specify .358 for their lead ".357" bullets and presumably their bullets meet that measurement, making it a little easier to fit them into the case -- if it is belled just enough.

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S&W Rover