Glad that it seems to be working for you. Despite your hesitancy to chamber live cartridges at home, I would suggest that they don't represent the loading experience accurately - as they are "chamber sized" from firing and have not been resized to factory dimensions... the lack of a bullet, i.e.: sharp case mouth wouldn't do anything to help you either.

Seat some bullets in FL sized, unprimed cases to practice.

My double rifle experience prior to the 375 was a 470 and it does take a little getting used to - to chamber a belted round, but once you get used to the feel, it becomes second nature.