Well, turns out that it wasn't a T3X, but I bought it anyway.
If I can find a prefit 260 barrel I'll finally scratch that itch.
Until then I'll just run it as is. 👍
Unless I missed it, what was it then if it wasnt a T3x? If it were an older T3, so what. I have one in 308 and drives tacks with several different factory and handloads.