Is anyone doing these? If so, who?

Used to be Elmer out west, and Justin Sipp, but neither are working now.

Andy Binx is making barrel extensions. I was recently approached to do one. Looks like several 'special' tools would be needed. Don't know what kind of demand there might be for doing those. I'm about out of the mood to make tools I use 1 time and then store 'um.