Gee, I think I may know who loaded them for Matt!!! (With my stash of RL-22 that has been unavailable for quite some time).Yes, those Barnes TTSX work
Although my favorite loads in my 300 Win Mag are with the old Norma MRP (they discontinued it and came out with a replacement that is almost the same, not sure if it is still in production).
Matt's gun is a beautiful Model 70. Mine is my old Ruger M-77 (a bicentennial gun). Mine is a little shot out, and now only shoots well with bullets seated further out. It used to be a tack driver, regularly giving me 5/8" groups at 100 yds. I've taken most of my deer with that gun, using slightly downloaded ammo. My current load length does not fit in the magazine, but you can put one in the chamber and one under it, and a shorter one (for emergency) in the magazine under it, so if I want to use it I still can.