It looks like S&W made a change from the 1.0 to 2.0 in the barrel/slide lockup.
Here's my 1.0 ported barrel. Notice that the diameter increases towards the muzzle. Two different angles. Somewhere around 600 rounds.
PCore1.JPGpcore 2.JPG
Next is my Storm Lake unported barrel. Note the increased diameter also. Not sure why it's so much longer that the OEM one. About 100 rounds.
Stromlake.JPG
So my slide, at the muzzle has no ridge. The same is true for my FS and Compact (both 1.0).