Don't know why they do that, but you're right, just the one 915.

If you contact S&W I'd be interested in hearing what they say about barrel interchangeability. One of the barrels listed obviously comes with a barrel bushing but as far as I know none of the 3rd Generation Smiths had a barrel bushing.

I doubt that I'll ever need to replace my 915 barrel but I'd like to know j just for future reference.

Dave