Of th 8 T3s I've had / have,the lot have run from one holers to 3/4" guns. The most challenging was a 338 Win mag. Could just be because it kicked like two sons a bitches. The two best have both been 7 Rem mags. 22/250,25/06,243,30/06,300 WSM,338 Win mag and 7 Rem mag. Tika rings,Talley rings,Burris Signatures on a rail. Walnut stocks,laminated stocks,factory synthetic and Bell + Carlson. Pretty well did the T3 thing.
Mount up a proven scope.
Make certain the recoil lug is properly nested.
A good bench,front rest / bags would be a big help. If you don't have a good back bag borrow or buy one. Money well spent. I use my old Bald Eagle brand rear bag. A left over from my BR days. Protector Model can hook you up with the proper bag for your needs. Very helpful folks.