Ben, I’ve got a hammer gun with a cross bolt. There always seems to be some exception to the rule.

In addition to preventing the barrels from moving forward away from the face on firing, a doll’s head or any sort of rib extension also provides some lateral support similar to side clips. As Daryl said though, I really question the benefit of the former over the later, because I’d think a gun would have to be severely off face to begin with for it to be of any value.

Since the lumps are well below the bore axis, I’d imagine that preventing rotation about the hinge pin would be by far the most beneficial function of a third fastener, followed by lateral support. While a properly fitted cross bolt does this, so does the c-bolt, screw grip, doll’s head with bite, etc.

The key is ‘properly fitted.’ Without that all of them are just for looks.

I think the jones action has a good reputation for strength because it actually torques the barrels to the water table rather than just hold them there. Any action type will lock up tight when new or in good repair, but after 100 years of wear and tear and questionable maintenance this is where the jones may offer an advantage, (that is, stay functional a bit longer into the wear cycle). I’ve seen several where the lever went a bit farther to the left than normal when closed. I supposed that this was the ‘self adjusting’ attribute in play, that is taking up the wear on the bites and ‘screw.’ Again though, really only an advantage if the gun is worn past the point of requiring maintenance in the first place, like a poorly fitted dolls head without a bite in my mind.

Bottom line to my ramble, while I think some designs are better than others from an engineering standpoint, proper fit, care and wear are much much more important. A lot of guns do just fine with only 2.

Bob