I thought about converting my G21 to 50 GI or 45 Super and I went with the Super. I basically did what you did with the guide rod and recoil spring. It seems to work great. I converted my 4506 about two years ago and prefer shooting that in 45 Super. Both of them work fine with 45 ACP or Super. I have not tested it for velocity but both are fun to shoot.
I only fire about 150 to 200 rounds of super through each one. Maybe a little more through the 4506!
I only fire about 150 to 200 rounds of super through each one. Maybe a little more through the 4506!