Hi guys, I have a Gen 3 21SF rigged up for shooting .45 Super( LW 6" barrel, ss non-captured guide rod, 22lb. ISMI recoil spring and of course, new .45 Super brass). I love the grip and texture on my new Gen 4 20 10mm. So much so, that I may sell or trade it in to get a Gen 4 21. I may be wanting to get the Gen 4 21 and get it set for shooting .45 Super as well as hardball. I know I would have to get a RSA adapter to use Gen 3 springs and guide rods for the Gen 4 slide. Just curious if anyone has done it yet. Thanks! Wanna kill these ads? We can help!