Nice shooting Phillip... what did you do to tune it to that level of accuracy?
Usual barrel tension screw, fore end bedding?

How did it shoot out of the box?

IMR 4064 = ADI 2208, a good powder in my .303 too.

Yes, the throat on the Ruger No 1 .303 is almost unbelievably long... I could just touch the lands with a 215gr bullet barely seated in the case.

Why I'll never know... unless some corporate lawyer thought people would fire surplus MK VIII machine gun ammunition through them and the longer throat would help drop pressure?