Graybeard, since you had your reading glasses on I thought I had better look at mine again to make sure I was not talking out of my you know what.
My 20 does have a bulge. You cannot see it when sighting down the barrel, but if you look at it from the side you can see it. The barrel measures .705 till it gets close to the back of the choke tube, .760 right behind the choke tube and .782 around the choke tube. I also measured my Benelli and it also tapers to a larger diameter at the choke tube, but for some reason the point at the back of the tube does not seem to stand out. I was going to measure the 870's but they were too far back in the safe.
Now to retract some of my original statement, I was originally looking at this gun in a 12 gauge and the bulge really stood out. even when sighting down the barrel. I was at the gun store tonight and looked at the 12 gauge again because of this discussion and the bulge is much worse compared to the 20. The 12 is obvious but you really have to look for the bulge on the 20 since you do not see it when sighting down the barrel. Maybe the smaller bores are even better.
Does not much matter to me whether it is there or not since I cannot see it when sighting down the barrel. I think these are a good quality and nice looking SxS for the money.