While I haven't tried it myself, the GM IBS drop in barrels for T/C are supposed to fit a Lyman Deerstalker, with possibly just some slight modification like shortening the under rib. At least, that's what Track of the Wolf says on their web site, under the information for the GM IBS barrels. I have put a GM .50cal flint barrel on a Lyman Trade rifle and all it took was shortening the under rib a tad and filing a bit on the sides of the breech lug.
