As one who is heavily involved with the LC Collectors Association, I can tell you for a fact that we have yet to find an example; or any evidence that Hunter ever manufactured a 20-bore on the standard "R", or Regular sized frame. Having made that statement, we would never state unequivocally that such a gun does not exist; only that we've yet to find it. If one does surface, we certainly want to see the gun!
Smith did made a light weight 16-bore on the "R" frame, and continued to do so for 10-12 years after the introduction of the "FW" featherweight frame in 1907. Also, we have yet to discover the significance of the R suffix stamped/seen on many of the featherweight frames prior to 1919; but as noted, it is not an indicator of frame size.
On another note, an FW framed 16-bore A2 grade Smith gun with two sets of barrels was recently sold at auction and should be in the possession of the new owner in a few days. It was advertised as having two sets of 16-bore barrels; but the shipping records have the notation "16/20" in the barrel column. Once the gun is received we'll examine the gun to verify bore size; but if this gun is a two-gauge/two barrel set, it will be the first such Smith gun I've ever seen.
