Not a T3 but my Rem 700 1-10 twist barrel loves RL 23 71g with the 200g ELD-X bullet in the sig brass with either a Fed 215 primer or a CCI 250 primer.  .75 inches at 100 yards.  Good luck.  This load may not work in your rifle nor will it be a safe load.  I did pluck it from the Hornady X book though. 

Sub moa-180 grains. 24” stainless barrel. TTSX, Federal Bonded Trophy Tip top two loads right now.
Rem 9 1/2 primer ,Hybrid 100v 67grns-3038fps OAL 3.335.
MOA-SST and Accubonds using 66grns of same powder. 2930 fps.
Loookg to try ELD-X 178s but the ttsx and federal are two excellent hunting and long range bullets.

SixShooter,

I should have shared this in my previous post. 

Over the years I have found the 300 win mag likes:
H1000 powder and RL 22 with the heavy for caliber bullets 180 on up.