He says the Navy cylinder can only be bored to .40, that's why the 60 Army has a stepped cylinder. So there still was never a 51 navy in .44
Hawg it(barrel)was bored to a .40 caliber and a .44 is a .40 caliber.
The cylinder(.44 same as the now 1860) was made with the rebate in it and the frames were stepped. The cylinder,stepped frame,and bored barrel were the Proto type Hawg and it still exists in the same museum.(((whew)))