Mine shoots Hornady ELDX really well. Federal accubonds are only giving me about 1.5 MOA. The 150 grain Federal blue box powershock also shoots really well.
My rifle is the older T3 SL In 7RM and shoots the Barnes Vor TX 160 grain very well. It also shot the 150 Core Lokts to MOA Before I switched. Would not shoot the Federal 140 grain with Nosler. Could be it just liked the heavier bullets. Good Luck in your quest.
I just got a t3x light in stainless too. Added a limbsaver pad- have the vertical grip and trigger spring but haven’t added them yet. Viper pst 4-16x50.
It shot the cheapie American Whitetail loads well which were just something to break it in with.