I don't know jack about what is a snubbie, but for me the barrel length has to take in to account the frame size.
I don't think a 3" j frame is a snubbie, but a 3" N frame 45 is.
I am probably way off base, but for me it has to do with proportion size of the barrel to the frame, rather than just the length.
I am sure somebody will be along to set me straight any minute now.