I've acquired an itch for an 11mm Mauser of one sort or another. What 'waves me off' is the case forming. I thought I saw a drawing of the Mauser A-base (hope this is the correct term) here but my search efforts are not paying off. Any help would be appreciated.

There are a number of sources on the 'net which talk of using .45-90 as a parent case but it is still unclear to me. Any insight in case forming will also be greatly appreciated.

Thanks!
Hoot

Here's some info. https://castboolits.gunloads.com/showthread.php?341411-43-Mauser-Case-Forming

The Mauser "A" base is the M88 case base with thicker rim with the concave edge, the head diameter is about .468". The case you need is the "Mauser Base" or MB case, The head diameter is about .515-.516"(actual commercial cases I have measured were .510") with the thick concave edged rim (rim diameter shown as .585" but most rim recesses accept .595", which is important to center the case for even fireforming). I make cases for my 11.15x51R (MB) using 45-70 cases and friends make 11.15x60 R cases from 45-90, using my method. When I started the project, I tried making them from belted magnum cases and from 8x50R Lebel cases. These donor cases made useable cases (for the 11.15x51R) but were much more labor intensive than the 45-70. Using belted cases, I had to turn the belt off and swage a blank brass rim onto it with the brass flowing into the extractor groove. Then I had to lathe turn the rim to size and shape using the shell holder as a gauge. Once this was done the cases were die formed, trimmed, then fireformed. With the 8x50R cases, I had to swage the heads to size, using 4 different shop-made dies in about .010" increments. Due to "spring back" I had to swage more than the calculations indicated, and I cut a parting tool width groove in front of the rim to prevent closing up the flash hole. For power during the swaging operations, I used a cheap "Truck Load Tool Sale" H shaped Hydraulic press. When using 45-70/45-90 cases, I made a button die to move(bend) the rims forward using the press and a rod inside the case to push it into the die. after die forming and turning a parting tool width groove ahead of the rim to make bending it easier (without the groove in the first trial, the rim sheared off). after bending them forward the rims were turned to .595" to closely fit the rim recess to evenly fireform the cases. The 45-70/45-90 cases were much easier to make MB cases from and the small difference in head diameter caused no problems once the cases were evenly fireformed. Using standard dies, the cases expand to fit the chamber only once, so work hardening was not experienced. As is my habit, I still adjusted the loading dies to headspace on the shoulder. Depending on the rifle you acquire, if you don't want to use black powder, you may need to use a bullet up to .452" in diameter, which requires special efforts. In my experience Mauser Mod. 71/84s are more likely to take .446" bullets than Mod. 71s. Break open rifles bullet diameter was up to the maker.
Mike

Thank you both! Much useful information.