Can you clarify how many grains you are putting into the round?
Have you measured the case neck to insure you have taken all the flare out? Take the barrel out of your gun and drop one of your reloads in it. It should spin and "plunk" in the chamber and should be near flush or below flush to the breech end of the barrel. If you push on the round and then turn the barrel over, the round should fall out.
I would suggest you seat a bullet in an unprimed case to 1.115 and see if it sits lower in the barrel than the one you just tried at 1.120. Keep seating the bullet a little lower until you get to where the round isn't getting lower. Somewhere around there is your maximum COL for that bullet.
If you seat a bullet at 1.115" and the round doesn't get closer to flush, it isn't the bullet profile but the diameter somewhere near the neck. Check your crimp and insure you are removing all flare.