good idea, except with a real hamr barrel you get the 15" twist.
That's probably worth about 5fps and 1/24" in group size. Fact is, I get the same velocities from the 7.62 as the loading data shows for the 300.
I assure you that you can't come close to 300 HAM'R velocity with the 7.62x40WT at the same chamber pressure. If you want to compare 7.62x40WT over pressure loads to 300 HAM'R safe pressure loads, then yes they can be very close.
