You just need the old P220 mag with flush metal base, and you are gtg. Do not get any mags that have the rubber or polymer base, because they add thickness to the length, hence not allowing the heel mag catch/release to engage. The 8-rounder is such an example.
I should add that, the old mag with the flush metal base that you want can either be for the side mag release style gun or the heel release one (like on the BDA .45).
I should add that, the old mag with the flush metal base that you want can either be for the side mag release style gun or the heel release one (like on the BDA .45).