775A post manufacture Super Choke factory add-on

After many years of trying to find a shotgun that fit well enough to compete, I managed to "fall into" a Savage 775A in 12 gauge with a factory installed "Savage Super Choke". Much to my surprise, I was able to point & shoot Sporting Clays with great success. I attribute the success to the exaggerated drop at the comb & heel of this model. Unfortunately, though made of real machined parts, they were not designed to see hundreds of rounds per month and tend to break down. I have acquired five such units, three of which are still fully operational. There is one that seems a little odd. It is the reason for this post. One of the three I have has a little shorter barrel than the rest and it is roll stamped "FULL" near the receiver. The choke is a Savage Super Choke like the rest except there are fewer slots in the compensator portion and they are a bit wider. It is my guess this unit was made as a "FULL" choke & later sent back in to have the company put the "Savage Super Choke" on after cutting the full choke section off. Can anyone validate my assumption or add to it? Thank you & safe shooting - oldwrench