The Fox Supers, in 12 and also in 20 gauge, were designed as long range waterfowlers. The "penultimate" 12 ga. Supers are the ones marked as originally having 3" chambers. The chambers are reamed in a certain manner, with a certain taper that is unlike other 3" chambered guns, and require sophisticated measuring to determine originality. There are also 2 3/4" chambered Supers that are original. Supers are unique in that they were designed for a particular waterfowl load that was developed by Western as a long range waterfowl load. If I am not mistaken the HE grade Super Fox is the only gun ever designed and built for a particular duck load. It has a different frame size than other 12 ga. Fox guns, and has specially bored bores and chokes to hold tight patterns at longer ranges.
The L C Smith that was designed as a long range waterfowler is the 'LONG RANGE', and so marked on the underside on the through lump. However, the first year they were offered for sale (1924) the Smith LONG RANGE was SUPPOSEDLY not marked as such.
There are many, many iterations of American made shotguns that are effective long(ish) range waterfowlers, but the two I mentioned were designed and advertised as long range duck guns. As mentioned above, there was a small area of dedicated small bore duck hunters in California, and there are examples of guns having been ordered for members of those duck clubs. I have a Parker DHE that was originally sold to that area. It has 32" 16 ga. barrels, and another set of 32" 20 ga. ones. I have no proof that it was ordered for, or by, a member of one of those clubs, but it is a sweetie on the dove field.