After I saw his video, I took a look at my bobcat mk1, which lies in parts, and compared it to my mk2 wildcat, both in .177. I have no plans changing barrels on them, but wanted to check out of curiosity. It seems it will not work on those 2 particular guns, as the hole in the breach for the barrel is smaller on the bobcat, and the metal part of the x-barrel has to big diameter to fit into the bobcat. But since he make the change on a boss, which has basically the same block as a royal, and bobcat, I would guess it will work on the bigger caliber guns, but maybe not all calibers?