Sorry to hear about the feed problem.
It is not cost effective to modify molds, and in any event, there is no way to cut a smaller meplat. You can only remove metal from the cavity, you can't put it back.
Dunno much about M600s, but the M700s will feed most anything after tuning (mostly tweaking the magazine so that the cartridge pops up pointed toward the chamber). Out of the box, they don't feed much of anything except spitzers or round nose.