We do not have a adapter forBB guns. BB guns are not the best to suppress due to the loose tolerance of the barrels. The BBs tend to strike the baffles in the suppressor destroying it internally.
We do not recommend moderators on BB pistols. Sometimes it works out OK, and a threaded barrel would be the way to go
Our concern is about the relative and accuracy of smoothbore, short-barreled pistol slinging copper coated balls into the monocore and damaging it or ricocheting in a dangerous direction.
If you get it threaded, go with 1/2x20 UNF threads.