I am looking all over for the answer, as there seems to be a huge range of gas check shanks for 41 caliber's. Sage's lists 3 different sizes, and oddly the "416 rifle" size seems to be the most common for 41 caliber handguns. Both NOE and Accurate have 41 mag designs with a .391" shank. While not a big difference, Sage's lists .393" as the correct shank size for 416 rifle, while I have yet to find a design that size.
I am designing a mold, and would like to know which one, if any, is more popular or common than the others.