Indy,
What load were you using for the TSXs?
First, I will caution EVERYONE to work up to my load in YOUR rifle. It showed no pressure signs in my post-64 Model 70 but might in some other rifle.
I used new cases, Federal 215 primers, and 72.0 grains (I weigh every charge) of AA2230 with either the 450 grain TSX or the 450 grain North Fork flat-nosed solid. Velocity chronographed 2250 with both.
Another caution: North Fork warned that flat-nosed solids can cause feeding problems in some rifles. They didn't in mine.