Mike Venturino had an interesting writeup about Bertram brass for the 45-75 where at the time he was working on his book "Shooting Lever Guns of the Old West". At that time Bertram brass for the 45-75 was unformed - but correctly headstamped - it was a slow process for him to properly form the cases as any crease would grow as the piece of brass went through the forming steps. Took him 8 hours to do 50 pieces of brass.
That said, it would be good to check if Bertram brass for the 45-75 is still unformed or if that has changed to a formed case that just requires the usual full length sizing, etc.