I've looked at several of those 80%. and shied away from them because I don't think there is any metal, but plastic that the slide runs on.The Polymer80 Glock frames come pretty close to just assembling a gun. You have to drill three holes and trim some plastic, and the ‘gun’ comes with a jig. After 15-20 minutes with a dremel or even a pocket knife then it’s just parts assembly. I don’t think you save any money that way however, because buying all the parts seems like it costs more than if you just went out and found a used Glock somewhere.
Most, if not all all of 80% 1911s are aluminum. And once the the cuts are made, the slide would be running on non anodized metal. Maybe if one could get a raw aluminum and after the cuts and fitting, have it anodized.
I'm curious of the P320 chassis, and the type of metal they use.