Geez, you're gonna get me in trouble. I'm guessing the brit has .45LC case dimensions? Would be interesting to swage the neck down to .355 and use the gelatin capsules. Hmm...303 Super Wasp Destroyer?
They are surprisingly tough. One of my pics on here has the overfilled capsule sticking up out of the brass before seating. Probably 3/4".
And yes, this has been fun.