I finally received the .58 Roberts lathe turned cases . Unfortunately, some of them had been fired with black powder and then not cleaned, so they were pretty corroded and nasty. But most are in good usable shape. The problem with these is the case mouth thickness, about .025” - .027”. There is no way I can get a groove diameter bullet into these cases without modification. Groove size is about .594”, the case ID is around .578” - .580”. I can use an expanding minie’ ball, but really prefer to get a custom mould for a short, groove diameter bullet. But while waiting for the cases I ordered some .590” diameter minie’ balls to start out with. But these would not fit into the case. Well, I have a very old, well used bench lathe. So I set up a case in the lathe and inside turned the case mouth to about .594”. I’m not a machinist by any stretch of the imagination, but I managed to get one case done as a trial. The minie’ ball slipped in nicely and the round chambers – so far, so good. After I decide on the bullet design and diameter I want to use, I’ll order a chucking reamer of the appropriate size to ream the case mouths.
Here is a shot of the .58 Roberts dummy round with a .56-50 Spencer to its left and an empty .58 case and minie’ ball to its right. Coincidentally, the Spencer and Roberts cases are nearly the same length. The Roberts cases are 1.330”, the Spencer is 1.356”.
I always thought the .56-50 Spencer was a big round, but next to the mighty .58 Roberts, it looks down right puny
The next step will be to decide on a bullet design and order a mold from Accurate Molds.
This is going to be a fun ride!