A project I started and have yet to finish is a Colt 1991A1 Series 80 that will shoot (so far)
9mm
38 super
9X23
and of course 45ACP
I was looking for a 10mm slide so I could start adapting cartridges of that case head size/type before interests (and finances) changed.
I started with a used, but in good shape 1991. I found a new 9X23 complete top end that had been removed when the chambering lacked interest. A 9mm and 38 supper barrel came next along with necessary recoil springs and magazines. My goal was to adapt every semi auto cartridge between .354" to .45" to this frame by only changing the top end. So far it has worked better than expected. The biggest concern was the ejector. Would a 45 ejector kick out a 9mm head size case reliably. No problem!
Anyone else have project?

 

Nothing like that!

Got some pics?

 

Not much to it other than fitting your barrel ramp to the slide ramp.