I have a P250-22 that I got a couple years ago. I liked the modular feature where I could upgrade to different calibers but the 250 was discontinued and the various exchange kits are hard to find. I saw a kit that is a .45. Does anyone know if the frame on the .22 can accommodate that caliber?

IIRC, The .22 kit will only fit the 9mm, .357 and .40 P250s.

I can't find a link - but I'm also reasonably sure that the P250 .45 FCU had different specs (wider?) and was a one-caliber only conversion.

A P250 FCU works for all six calibers from .22 to .45. The P320 has a different FCU for .45 to allow its takedown safety to operate.

Whether used with a P250 or P320 FCU, .45 requires a different grip module with a larger magazine well because .45 magazines are longer front-to-back than magazines in other calibers.

I have a compact P250 in 9mm and a full size 45 caliber exchange kit. It works fine. As GC70 noted the P250 FCU is the same for all calibers.