Happened to find a couple hundred 401 Herter's mag. Never loaded for it but essentially a 40 cal revolver I think. I just had to buy it. I am pretty sure I have a set of dies for the caliber too...somewhere
I would definitely buy any .401 brass or ammo I came across even without the revolver. I have seen only a very few of the Herter's SA revolvers at gun shows. They were said to have been very well made, also available in .357 and .44, I think. Herter's was located in Waseca MN, add they also operated under the name of Ruhr American. Their catalog was the ultimate wish book, they had everything at cheap prices. Of course, everything they sold was the "World's Finest." I used to buy most of my reloading stuff from them, and still have several die sets. I sort of remember that their primers were made in Japan. I could never keep a Herter's catalog. Someone would always steal them. They were wonderfully entertaining. Those were indeed the good old days.
I may have mentioned this in an earlier posting, but Herter's also had a mail-in gunsmithing service.
An old Ruhr-Amarican catalog offered on eBay:
Ruhr American 1966 Gun & Fishing Catalog (Glenwood, Minn.) | eBay
My dad and I were big into Herter's. The catalog was looked forward to more than the Sears Christmas catalog. We had all kinds of Herter's stuff--fishing lure kits, muskrat trap, camping gear. All of it was decent enough quality. But the one thing I wanted but never got was the SA .401 Power mag! I wish I had nabbed a load of the barreled rifle actions too. I still reload on my Herter's Model 3 press and use the Herter's powder dropper.