I've seen this issue with re-barreled Mauser type rifles. Often it's a case of different case profile vs the standard but in this scenario, that shouldn't be a problem. I'd be looking at something like the last round working it's way forward due to the recoil of previous rounds fired and dragging on the front of the magazine or at the shoulder.
If you load one round and cycle the bolt do you get the same misfeed? If you fill the magazine and cycle the rounds through the chamber w/o firing, do you get similar results?
Let us know as there are some very experienced people here who are generally willing to help.