That's a modified choke. Older barrels are supposedly softer than newer barrels and the "safest" advice is not to shoot steel or htl. The problem is non-lead shot has not much "give" and if it "bridges" shoulder to shoulder in the choke area, ringing or bulging can occur. However, small htl, such as TSS9s, 8s, flow better than larger shot and have not caused problems ringing or bulging older barrels. I wouldn't shoot larger than #7 out of your gun. If you are worried about scratching or scoring the barrel, don't shoot htl shot. I've not had it happen in my guns, but if a shot gets between wad and barrel it will scratch the hardest steel, old or new. I have heard from a barrel/choke maker that he has heard of a few Benelli's having been ringed by federal FC wadded htl loads. Apparently the Benelli was slightly undersized and the wad's OD larger than the barrels ID. I'd try some #7 2 3/4" loads and see what happens. You may be surprised.
PS. Don't look at me if your barrel bulges. See sentence #2.
