Very good info. That reamer is doing OK then.
I had a 9X56 Mann/Scho that would not allow un-sized 358 bullets. I drilled a hole through a 7/8"X14 bolt and bought a chucking reamer to make a .3550" bore then lapped it to 356. I used Remington bullets and rolled them in STP and pushed them through.
Worked fine!
But if the neck is not too tight in the chamber (your reamer obviously is not) you could load the 358" bullet and fire them.
As I said, the trick is just working up the loads to function and be safe. Might even be fun.
Oh you can still get .356" bore barrels from Lothar Walther. None are made in the USA as far as I know.
I also know of no .356" bullets available here, but there are still made in Europe, but if I had a 9X57 I would not bother trying to get any. I'd just size them myself.
