"I cannot imagine any inertial force generated upon firing that would rotate a top lever to the right, "
Think of the stout sprng inside a Benelli bolt. It is compressed by the inertia of the rear half of the bolt during the first recoil phase. Compressed enough so as to unlock the action and perform primary extraction of a fired shell when the phase changes.
A top lever with more mass on the left side than on the right, and I have seen some so formed, at the end of the recoil phase, when the gun decelerates on the shoulder of the user would turn under inertia. I suspect the problem would be worse if the spring was also in line with the barrel axis.
In the Benelli autos we know the need to have the user's body to stop the main mass of the gun and thus initiate the second inertia phase, where the bolt travels back due to its inertia. Firing one from the hip can lead to failure because it does not allow the bolt's inertia to act.
Also think of how single triggers utilise inertia, though in smaller parts and weaker springs, or how safeties can self engage.
The camming open view somehow does not mesh with Greener, page 135 The Gun and Itse Development: "... the strain exerted by the force of the explosion is in a line with the teh axis of the barrels; to support this strain the double grip affords no power whatever. The work it [the double grip] does requires no particular strength. For the barrels may be held to the bed of the breech-action body by the thumb and forefinger, even though a full charge be fired". Greener seems to discount any camming force being exerted on double gun locking parts.
Definitely interesting topic. We need some high speed video of controlled experiments. A problem gun fixed to a free travelling bed to see if the opening can happen without the user's body stopping the main mass of the gun.
Or a more crude experiment of tying a problem "self opener" to slings and firing it. See if it would open under free and unhindered recoil.
Last edited by Shotgunlover; 03/22/15 06:39 PM.
