Good points, SL.
Over the years I have seen some strange damage to double guns but have yet to see a sheared cross pin, even in folding shotguns that have totally unsupported cross pins.
You never will, either. We are talking about double shear strength here, not single shear. For the hinge pin to shear it would have to shear at both ends, simultaneously. Ain't gonna happen from the forces generated by firing a shotshell.
I am about as far from an engineer as one man can be, but I deal with double shear situations daily on the farm. We pull subsoilers as deep as 18" in compacted soil. It is being held in place, until it hits an obstruction (stump, rock) by a Gr5 1/2" dia. bolt that does not have any tension on it from a nut, i.e. it is not being "squeezed together" to increase the shear strength. Gr5 is very similar to 4140 in strength, according to the charts I have looked at. Using a simple analogy of a 3/8" cross pin, or hinge pin, it doesn't take an engineer to see that there will never be a sheared doublegun hinge pin caused by any force that can be contained in the chamber and fired off a man's shoulder.
