I think this all depends on one's definition of "Frame Size". To me, the entire frame should be proportioned to the gauge. For instance, I have 12 gauge Lefevers which have three different sizes of standing breeches & firing pin spacings, but all have essentially identical bars & frame bodies. I personally do not call these different Frames. Parker Bros did which is why they listed so many different frame sizes.
I have a little 28 gauge American Gun Co (Crescent) hammer gun which one can see at a glance was built on a frame dedicated to the 28. The bar is quite slim & in proportion to the gauge, weight 5 lbs. A 28 weighing in at 6 lbs or more was likely not built on a truly dedicated frame, other than the size of the breech balls.
