If you guys are still reading here... I have a W. German P220 and the conversion kit mags will not seat and lock properly. The mags drop free as if there were no mag catch at all. I've found others who have had the same problem. One fix that I found on YouTube was to cut a slot in the mag body and apoxy a cut in half #10 washer in place. I haven't tried that yet and I'm not sure that I will even try that trick until I've exhausted all other options. I truely wish that someone would manufacture a quality metal mag for the .22 kit.
I've been a Sig fan for over 12 years and I have enjoyed my current P220 .45 for at least as long. That said, I have lost a great deal of respect for Sig due to the shoddy quality of these kit .22 mags. Come on Sig... Seriously??? Plastic mags that do not even function properly with your product? I have had the kit for over two years now and have never been able to fire a single round due to the crappy mags. Needless to say, you're charging the same price for crappy plastic as you are for steel .45 mags.
I called Sig and they wanted me to send the pistol and the kit to them. I can't be caught without my carry sidearm for a month or longer. Plus who wants to risk that the shipper might lose my weapon. I've heard way to many horror stories.
Note to SIG:
A proper steel mag would remedy the issue.
This is my .02 worth of opinion pertaining to the kits. I say venture forward with caution.