For whatever this is worth, some years ago when my ignorance equated to bliss; I took an early A Grade Fox (no original finish and with rough bored, but a solid lock-up), had the chambers lengthened to 3" and the chokes opened to improved cylinder for the specific purpose of using the gun as my "water-fowler". At that time, steel for ducks was the only option; so I purchased the heaviest 3" steel loads I could buy (which I recall were 1 3/8 oz loads), and headed to the swamps. Like everyone else, I had read that steel shot would score grooves in the barrels; but, with rough bores anyway, I could care less. I was also ignorant as to chamber pressures generated by steel loads at the time; but those using such shells during these early days with steel will recall that all the hype concerned bore damage from the hard steel shot; there was no press on pressures these shells generated, nor did ANY maker post pressures on any of their shell boxes at that time. The bottom line was that that the steel shot in those shells was so well protected by an extra thick wad there was never any visible additional damage observed to the bores of the old Fox. Further, I was amazed that there seemed to be so little recoil from those loads; it was if I were shooting skeet loads. That said, I've never tried steel in Damascus barrels and don't intend to; further, I don't recommend anyone duplicate my experiment with the Fox or any other vintage gun. And by the way, many of those old 10 pound, 10-bore Smith guns were used for target and live-bird shooting. I am working on an aritcle at this moment about just such a 10-bore Smith gun that, among other feats, was used to win a B Grade Parker hammerless (the grand prize) in a large 1893 Ohio competition.
