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Double Rifles, Single Shots & Combinations >> Building Double Rifles & Gunsmithing

Carpetsahib
.333 member


Reged: 29/04/07
Posts: 435
Loc: Western NC
Re: O/U actions
      15/02/10 01:29 PM

Quote:

With break open guns, the issue is keeping the barrels on face. It's as much a matter of geometry as it is mass of metal. Break open guns try to open when firing due to the push back on the breech face and the barrels wanting to flip down from the bullet travel. Barrel wall thickess is enough to keep the side expansion in check, or the gun wouldn't last but a couple of shots. The pivot point on an O/U offers an advantage as it takes some of the leverage away from the barrels wanting to flip down, especially for the bottom barrel.


Forces required to keep the barrels on face is something that I have been interested in for some time. If one looks at the forces involved when a break-down gun is fired, the following are obvious: 1. Back thrust of the cartridge case upon the standing breech(+) 2. Forward thrust resulting from the projectile engaging rifling, and then friction whilst traveling down the barrel(+) 3. Friction of the case head upon the standing breech (-). (N.B.: The (+) symbols indicate a force that tends to open the gun. The (-) symbol indicates a force that tends to retard opening the gun.)

The pivot point is at the cross-pin, and that is usually offset from the bore axis; therefore there is a force-couple, in effect a rotational force, centered around the cross-pin. If the cross-pin was coincident with the bore axis, then the effective force-couple would be zero, and the action would tend to remain closed, even in the absence of a positive lock. That being said, the action of recoil against a pliant surface, i.e., the common human shoulder, would tend to break the joint and the gun would open in actual practice - if there were no positive lock.

Quote:

Actually, my opinon of what would make the ultimate action for strength...a snap action ( side lever for my taste) trigger plate lock ( the lever cocks the hammers, the lockwork behind the action body so the bars remain solid) clamshell with Bissel rising third bite. That would take some serious punishment......hmmmmm


I like your ideas; however, I wonder if the Bissel rising bite is any more effective than a properly fitted Greener cross-bolt. Is there more mechanical advantage with the Bissel due to the locking surface being somewhat further removed from the pivot point?

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Entire topic
Subject Posted by Posted on
* O/U actions whitey 13/02/10 04:49 PM
. * * Re: O/U actions 4seventy   13/02/10 05:50 PM
. * * Re: O/U actions whitey   14/02/10 02:27 AM
. * * Re: O/U actions baileybradshaw   15/02/10 04:53 AM
. * * Re: O/U actions Carpetsahib   15/02/10 01:29 PM
. * * Re: O/U actions baileybradshaw   16/02/10 06:09 AM
. * * Re: O/U actions Carpetsahib   21/02/10 01:08 PM
. * * Re: O/U actions whitey   15/02/10 06:36 AM
. * * Re: O/U actions CptCurlAdministrator   15/02/10 11:17 AM
. * * Re: O/U actions doubleriflejack   27/02/10 10:01 AM
. * * Re: O/U actions whitey   15/02/10 11:58 AM

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