I recently purchased a Fly45 and I have been using this adapter so that I Can attach a three lug Mount. The actual CB2BA adapter has some sort of hexagonal nut on the periphery. Does anyone know what size wrench is required to fit? Measuring it, it comes out to 33.3 mm.

If all you're asking is what US wrench is 33.3mm -it's a 1-5/16"
33mm =1.311    
1-5/16 = 1.3125"

On the other hand, if that's not your question:

The CB2BA adapts to the CB muzzle device system; not seeing how that can be used in any with a 3 lug system, and CB brakes are not made in pistol calibers.

The FLY 45 booster basket system adapts to standard HUB; that would seem to let you adapt just about anything.

Suggest contacting TBAC; they have always been lightning fast in answering my questions.

Thanks