We have a Snub "BUG" Division for Defensive Pistol ( similar to IDPA)
The Club also has a 'BUG" Division for our ICORE Revolver Match's as well. (Not a sanctioned ICORE Division).
Our Rules say 3 Inch and under is a snub. Note: This is a small turn out Division, so we have not refined the Rules any more than barrel length.
The fly in the ointment with a 3 Inch Barrel would be in larger revolvers. We have several Willy Clapp 3 Inch GP100's shooting at the Club. I have a 3" 66-2 and a 3" Adjustable Sight GP100. While legal no one enters their 3" GP100 in BUG Division. When I shoot in the BUG Division it is normally with a 2.25" SP101, my 3" SP101 or my 64 Snub with 2 " barrel.
It is really hard to draw a line in the sand at 2", 2.5" 2.75" or 3" on what is a snub.
The 3" J Frames, and the 3" SP101 are still what I would call a snub.
The 2 Inch and 2.5 Inch K frames, and the 2.75 Inch Security Six are normally considered to be snubs by most as well.
It is hard to justify a 3" K Frame, 3" GP100, or a 3" 686 not being snub's in the match rules.
Just My 2 Cents
Bob