I’ve shot Production with my G21 for years, I reload, so my cost is low. I have to load to a pf of 150, to get the slide to return correctly. The recoil is less than a 9mm, which is good when your friend Arthur is in both wrist. I use 200 SWC, mainly Bayou Bullets, and some Black Bullets. I love that big hole. I recently had Pike (http://mod1firearms.com) add a Trijicon RMR to my G21 for Carry Optics, and my G19 for Steel and GSSF. The G19 was my EDC for a few months.
Sadly Life gave me a kick in the A$$, and I discoverd I have Neuropathy. It’s not a good idea, to be running with a loaded .45, when you start to lose your balance. So I sold my G19.
I still plan on shooting Steel and GSSF (Open) with my G21. I sent a Certificate to GSSF for another G21, they’re just like a kid, you can’t beat them. You will enjoy shooting your G21 in Production.