I agree with the conclusion that steel would not be beneficial to shoot through a pre-steel browning, regardless of choke. Two issues, as stated the steel used in barrel making was of a different hardness, than post steel construction, even then my invector plus tubes much tighter than imp mod. are not steel recommended and browning chokes of that vintage, are notoriously tight! with imp cyl. regularly patterning as a true mod. and mod. patterning as full with normal lead shot, steel agravates the problem further. With eventual ring bulge as a result, while not a functional issue for the most part, it may seperate or cause rib distortion, and assuredly it will devalue the gun to zilch. I have seen guys have Briley thread thin wall chokes into the barrel that are steel rated, or buy a current barrel that fits, of current manufacture, that's steel rated, saving the original barrel.