Right answers, wrong question. Needless to say, if you affect the end of the barrel (i.e. adding a can), you will affect the POI.

The question is, with the can on (assume direct threading), how consistant is the POI? Thunderbeast are great. And any quality can, should have consistant POI.

Key for shooting is your data book (one benefit of being a competiitve military shooter) and being able to screw on the can, crank in the adjustment, and be 1/2" MOA on the first shot.

FWIW