So the groove diameter takes a Mag in a 63?
There is only .0015 difference between a Long Rifle barrel and a Magnum barrel. Have had zero issues with not only the 63 but also added Model 48 cylinders to a 17 and an 18...all shoot great.
I think I have about a half dozen of those Bushnell Phantom scopes... Had them on TC Contender barrels and also my favorite Model 53 .22 Jet... Very clear tough little scope...
Bob