The D M Lefever built by Uncle Dan after he left LAC used a single crossbolt as the only bolt for holding the bbls closed & also assisting in axial thrust. None of the rest of this gun of course looks like a D M Lefever. In the 1905 catalog it was stated this bolt was 5/16" in dia which, working in conjunction with the hinge joint should hold anything a man could fire through it.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra