An odd question, but I saw this over on the Glocktalk forums where a poster said they have a P225/P6 with a P228 slide and barrel on it.

Is this even possible? I know the barrel length is the same, but I would have thought the slide dimensions would be a bit different to make this not work.

Their barrels aren't the same part and neither are their locking inserts. As I recall, however, someone put a 9mm P229 slide assembly on a 357/40 229 frame by first installing a 9mm locking insert. Perhaps something similar is possible with the 225 and 228.

It's hard to imagine what would motivate anyone to do something like that except under very unusual emergency circumstances.

i think it falls under the classification of "just because you can do a thing doesn't mean it's a good idea"