WB
If my research is correct, George Herter contracted
Wednesday, August 28, 2019, 07:04

Norma in Sweden to manufacture ammo and components. It is top quality stuff and still a great find some 50 yrs. later. .30-30 brass can be cut down and the rims spun down to work. I use .41 Mag. brass by sticking it on a mandrel I made to clamp them in my lathe to turn the case head down about 0.009". Sizing a .41 in a .40 S&W die throws up that teeny belt that has to be trimmed off to fit. Also the OAL of brass is 0.125", not the resulting 0.127-0.131" the .41 ends up being.

The 10mm rimmed magnum concept dates back to the 1930's and counterparts of Elmer Keith. They were taking 0.403" bore Colt single actions and boring cylinders for a cut down version of the .401 WSL from 1910 fame. Those bullets were actually 0.408" but whats a few thousandths? It worked fine. Even with the old No.80 powder I'm certain the 200-250 gr. bullets ran upward of 1400 fps. Pretty snappy and there was lots of meat in those old pre-war Colt cylinders compared to any other larger calibers of the day. You know someone packed a .38 case full of No.80 and tried it. Wonder what that did with the 158 gr.?

Today everyone needs a gimmick to capture interest. The 10mm is subject of lore now in semi-auto fame. Not totally undeserved, enough guys bought into the idea it is a cannon to actually have it in hand when a need arose, and it filled the bill. A rimmed 10mm mag. equals the .41 Mag. nicely but does nothing it cannot. I think if someone decided to resurrect it in a mid-frame like the GP-100 (with six-shots please) it would be an instant success, every swinging Dick would have to have the new one!