Philnie, probably the most reasonably priced mould that would makea reasonable CONICAL for the UMag would be the one by Rapine at Buffalo Arms (custom moulds - .504). It's $80 but comes with handles I'm told. MtnMolds is kind of out of business until he gets his new shop set up. The other possible source (expensive) would be something from NEI.

http://www.buffaloarms.com/browse.cfm/4,2228.htm

http://www.neihandtools.com/

You might also check with Dan at Bullshop to see if has any recommendations. I don't think it hurts his feelings to talk moulds. Also, you might ask over at http://castboolits.gunloads.com/- some pretty heavy duty casters post there.