Yeah, the larger shoulder cannon does look nicer on the HS figure, for sure. Unfortunately, I'd have to do some pretty significant modding to get it to attach. It's probably possible. The HS head comes off its ball joint by just removing the screw from the head. The HS ball joint looks to be quite a bit larger than the MS ball joint (not really a big surprise). The more daunting aspect is popping the MS head off without breaking the ball joint. I gave it a little pressure, but backed off pretty quick because of the level of resistance.