Toad:
It seems you spend a good deal of time in and around old mill bldgs. and the like, from some of your questions. You might do well to see if you can get your hands on a copy of a couple old books which were my Father’s ref. books. I’m not quite that old, I inherited them. “Carnegie Pocket Companion for Engineers, Architects and Builders,” Carnegie Steel Co., 23rd Ed., 1923. And, “Architects’ and Builders’ Handbook,” by Kidder & Parker, 18th Ed., 1931, John Wiley and Sons.
Kidder & Parker show the following for pins and bolts: Wrought iron, 12ksi tension, 7.5ksi shear & 15ksi bending; Steel, 16ksi tension, 10ksi shear & 20ksi bending. They used a net area which was probably at the root of the threads, because a 1" dia. had a net area = .55sq.in. and a 2" dia. had a 2.302sq.in. net area.
The Kidder & Parker book has some really interesting section on Steel, Concrete, Timber design from that era, as well as Rivets.