I reload for a Chilean mauser. For me, I have had very good results with H380 and IMR4064 in moderate ranges with the 139 and 140 gr bullet. The rifle is very accurate with just about anything. It will easily shoot 1.5 inch groups.
I also have a couple of spanish 7x57 with barrels that look like sewer pipes. With those, I am able to get 3 or 4 inch groups at 100 yards and do not expect anything better.