No, you can't, for a few reasons. The aluminum frame of the .45 P220 can't handle the recoil of the 10mm if you could find someone to make a 10mm barrel that would fit the slide. Bar-sto only advertises/makes 10mm barrels for the 10mm-specific slide.

There was also a recent thread where a few members confirmed that the dimensions of the rails between the two versions, both slide and frame, aren't compatible, so you couldn't use a factory 10mm slide and barrel.

If you could find someone to make you a 10mm barrel for your .45 P220, you would probably be able to use the standard P220 10mm magazines.

 

P220-45ACP magazines work just fine in mine, loaded one round short of full.

 

Thanks for confirming my thought that it wouldn’t work. Would be nice if it did though!

 

Perfect opportunity to justify a new Sig P220 10mm.

 

Just got one. It's a beast but soft shooting for a 10mm.