Bob, you make a valid point. Without any solid criteria, one must pick some dimensions to compare and cylinder diameter is just one of many dimensions to use as yardsticks.
I picked cylinder diameter as a convenient dimension to compare one type (a Taurus 441) against another type (S&W L-frame) mostly because hporter had provided those measurements in a prior post. I’m not suggesting cylinder diameter or frame thickness, or some other arbitrary measurement is a key factor, it’s just a convenience reference point between totally different manufacturers. Since there is no such thing as a Taurus “L-frame” (L-frame is a S&W term) the only thing we can do is offer an approximation to the known frame sizes used by S&W.
The underlying question by hporter from post #48 was, "I saw a Rossi 720 discussed, so I thought I would ask what frame size a Taurus 441 in 44 special might be considered? ".
Since there is no absolute answer to that question, the only thing we can do is come up with approximations. Sort of the same way that I would say that a Taurus model 82 is ROUGHLY the equivalent of a S&W K-frame. They aren't the same thing but they are roughly in the same class.