Jon;
I do not have a Tobin to measure, but going by the pictures the frame does not look any longer than the Lefever frame, or Baker or L C Smith for that matter. As far as holding the barrels Closed the further the bolt is from the hinge the less strain it has to bear. Is it easier to pry a heavy rock out of the ground with a 3-foot lever or a 6 foot one?
Just going by the pictures the bolt looks amply strong for the task. A lot of folks would be totally surprised if they did a smoke test on a lot of these "Multi-Bolted" guns. Most often one bolt is carrying the load.
Until shown otherwise I am still firmly of the belief that too much metal was removed from the bar, not leaving it up to the task at hand. The long frame itself is not a bad design as it has been used successfully on so many doubles. The steel in the bar must, of course, have an adequate cross section to give rigidity, but this also applies to short frame guns as well.
Most short frame guns, such as the A&D, if they fail in the frame, will do so by cracking the frame at the junction of the standing breech with the bar.
This was relieved somewhat, but not totally eliminated when it was learned there needed to be a radius in the corner.
