The cmmg kits don’t actually move the buffer at all, the bolt cycles entirely in the chamber, so your H3 buffer shouldn’t effect it. I actually have a dedicated .22 pistol upper on a lower without any buffer tube at all for compact plinking and it works great. I might have to print up a han solo lower though, that looks amazing.

Those things are loaded with fake butter. They’re dangerous if you have poor impulse control.