Yeah aluminum. As for the jams it's a failure to eject
I'm far from a gunsmith but I had extensive FTE issues with a polymer 80 that I resolved with an aftermarket extractor. If you have a lot of rounds through the gun (it does look a little bit dirty) I would do a full strip down and clean the absolute hell out of it focusing on the extractor and ejector, then lube those two up well on re-assembly.
For the pain from shooting, it's an aluminum frame so it's gonna hit harder and be snappier than a steel frame, but maybe a new recoil spring, and maybe if you're getting a new spring get one of the kits that includes a few different weight springs so you can try them out.
Might even be worth trying to sell the Kimber (should be worth a decent chunk, fudds have money and love 1911s) and get something a little more modern unless you're into the 1911. I'm a fan of the S&W polymers, particularly the new Shields if you're planning to conceal carry. They're cheap, reliable, simple, and for my hands at least quite ergonomic.
I agree with the other guy. I'd try a different extractor, then maybe a different ejector. Could also be "limp-wristing" snap-back from that lightweight frame.
How does it hurt your hand? Does your wrist get sore? It might be worth doing wrist curls or something in that case to strengthen your wrist.
I'm not a gun person, I just have a very casual interest in ergonomics.
The webbing between my thumb and index finger gets all the recoil
Could you take measures to distribute more of the force towards your lower palm? For example, gripping more tightly with your lower fingers?
I actually lose my left grip pretty often due to smaller hands and the thick grip and the way too much recoil
BUT! BU- BUT! MUH TOO WURLD WORS!!!!!
