Hi,
I've just acquired a W. German 9mm Sig p220.
Is it possible to convert this to a .45 ??
Thnx to all,
Chris H.

Yes it's possible, but since 9mm P220's are worth more than .45 P220's (because of rarity) it would be much simpler, and cheaper to sell/trade for a .45 than try and convert.

If you did want to convert, the easiest way would be to buy a complete .45 slide/barrel/breech block/parts/everything and a .45 locking insert + magazines for the frame and swap over. This is NOT a cheap option though which is why I would suggest you simply find someone to trade with.