Fitting gas block to barrel

[Scoots]

My AR project rifle is starting to come along, although it's going much more slowly than I'd like.

I just received my low profile adjustable gas block. I measured the bore diameter of the gas block and the diameter of my Oly barrel at the gas port. I either have to open the bore of the gas block .010" or turn down the barrel at the gas port .010" (hmmmm, I just thought of measuring the bore diameter of the old gas block ).

Anyway, what did you guys do to ensure a proper fit of gas block to barrel?

Thanks for your help.