.455 Hunter,

That's the kind of Model 10/pre-model 10 I like to see! Lots of character and, I'm sure, history.

I'm stumped on the serial number. I agree with an earlier poster that the number you gave should be from 1960 and should have the model number 10-1 stamped on it. Check the serial number one more time to be sure. Maybe someone else will chime in with ideas.

As for the loads you mention, they'll probably be pretty close at up to 25 yards, but you won't know for sure until you try.

Congratulations on your beautiful revolver!

Donald