I have some old 7 round P220 mags that need a good cleaning inside. How do I take the base plates off? There's a small pin-type on the left of the base plate. And.........where can I find new plastic ones?
Thanks

The “pin” you see there is actually the bottom end of the magazine spring.
Using something like a small screwdriver with small flat tip that you fit into the slot, push the spring up while sliding the base plate forward and off the tube. Be careful about where you’re pointing the bottom of the magazine when you pull the base plate off because the spring may leave in a hurry.

I never tried to “upgrade” that type of P220 magazine with a plastic base plate, so although I think it might be possible, I’m not sure.
If it is possible, you’ll need a new follower, spring, “insert,” and base plate. You’d have to see if vendors like Top Gun Supply, Brownells, Numrich, and possibly others might have the parts.

Added: I just checked a P220 magazine whose tube has the slot at the bottom for the spring to fit into. I was able to install the newer parts (follower, spring, insert, base plate) into/on the old style tube.

Added 2.0: This is what your magazine should look like disassembled.





This shows what the newer parts look like.

Thank you, it solves the immediate issue

As I have continuously been running into issues shooting IPSC stages with my P220/9mm 9 round mags (most stages in Canada are planned for 10+1), I was looking for an option to extend these mags.

I ordered aluminum baseplates from Armorycraft, which are made for newer style (45ACP) mags and cut a little slot into the side to accommodate the spring leg and lock the plate to the base. That extended the capacity to 10 rounds!!! Unfortunately in absence of the lockplate that these plates are made for, I had one mag fall apart and lost the spring at the range, so I played with it a little more. I took the lockplate from a P220/45ACP mag and combined it with my installation, which locked the baseplate properly. Since the lockplate takes a bit of space away I had to take a bit of material off the follower to retain 10 round capacity, but it all looks solid and appears to be working well.