Just a follow up on this thread... The Barnes XPB and MZ Expanders fit this Wiseman barrel very well. but will basically drop to the bottom of the of the GM 50 cal bores or even the one Lothar Walters barrel that I have.

I really want these to work in the GM barrels - so this morning I ran out to the shop grabbed a couple of files and knurled the XPB.



It now feels like it will fit the GM barrels just fine, it remains to be seen how well it might shoot from them.

The advent of the 50 cal. pistol sure has an upside for 50 cal ML shooters that might want to venture into the sabotless area...