The short barrels were most likely the original barrel set and are probably Damascus. Those barrels could have been damaged, thus the reason they were shortened to 17"; and the fact that those original barrels were damaged, is most likely the reason the barrels were replaced with a later set marked London Steel. As it appears the second barrel set was added at the factory, the current value of the gun will not be impacted; but the actual monetary value of the gun itself will be determined by grade, rarity, bore condition, bore size, and remaining amounts of original factory finishes. Grade O 12-bores are very common; so for the gun to have much collector interest/value, the gun itself must have tons of original finish, condition, and no after-market modifications. Finally, those shortened barrels may be perfectly safe to shoot with period correct loads; but the Feds don't allow the use of shotgun barrels shorter than 18", so keep the longer barrels on the gun. Best Regards, Tom