IMO, your problem is buying the barrel from TC. That's just been my experience in the past. I've had oversized chambers, out of round barrels, and throats improperly cut, etc.
The only barrel I ever had from TC that shot worth a hoot was a 22 hornet.
I got rid of everything else at gun shows and bought custom barrels. IMO, it doesn't matter who the custom maker is, SSK, VV, "B" Bullberry, they all make good quality barrels, only the price differs.
BTW, my 375JDJ was made by "B" and also shoots under 1" at 100.
Good shooting.
HL