doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Pressure vs recoil in old guns

How do I politely say this?

Bullshit

That is the only word that comes to mind.

[quote=TwiceBarrel Mr Rocketman I asked this question earlier and you either missed it or are just blowing me off but I would really appreciate an answer. I never intentionally "blow off" anyone. I'm sorry if my answers or the form of those answers caused you to feel "blown off."

What causes the gun to shoot loose? Metal to metal joint grinding and battering. Is it pressure which is contained within the barrel, chamber and ejecta? Yes, it is the forces on the joints needed to keep the joints closed while containing the firing pressure. Is it recoil which slams the barrels down, causing what we commonly refer to as barrel flip, that deflect the barrels which attempt to rotate around the hinge pin, place unequal torque on the hinge pin, puts severe stress on the locking mechanism(s) and batters the barrel lug against the frame which in turn transfers that force to the stock and finally to the shooter? No, you have intertwined the forces due to firing and those due to recoil. To understand the effects on wear and damage, you must keep these two sets of forces separate.


Just how does the pressure, which is contained within a closed vessel (the chamber, barrel and ejecta) (the vessel is not closed as the ejecta is free to move which requires conservation of momentum which generally assures recoil), transfer energy to the metal parts of the gun causing wear, as you stated in your previous response, when there is no way to transfer tht pressure exerted from ignition of the powder charge to the frame (pressure containment shows up as back-thrust force on the fences of the frame), forend iron, hinge pin (the hook and hinge pin absorb fore-aft force trying to separate the barrels from the fences), and locking mechanism(s) (the bolts and bites absorb the force trying to rotate the barrels upward from the action flats due to the center of back thrust force being above the hook/hinge pin center of force). [/quote]

You are doing great Rocketman, hang in there.
Too bad we don't have a stackup drawing to picturize all the roll centers, clearances, and the directions of the forces being applied.
It could be called, "Why a shotgun shoots loose", and be an FAQ stickey.

The timing of these controlled explosions (I know, oxymoron) moves through the shotgun like a wave. Each part accelerating like little dominoes. Heavy pieces being more difficult to accelerate, and taking a longer time of collision. Like catching a baseball. Human bucking up all the while, squashing the stock into the action.
Unfortunately, by the time the stock is accelerated, the chambers have been at,exceeded, and vented themselves due to the pressure.

So, I vote for excess pressure doing more damage first. Not to say, that as links in a chain, little weak parts along the collision highway could fail or be beaten to bits before the stockhead pulped. And be done below barrel burst pressure, or fatigue cycles entered the mix.

Sir I believe it is you that is intermingling the two separate forces.

Chamber Pressure acting upon the interior of the barrel, chamber and ejecta versus a totally separate force called recoil which has resulted from the ejecta being discharged from the barrel with an extreme amount of velocity (Newtons 3d law of motion. Remember recoil is totally independent of and not related to pressure. Recoil is only dependent upon the mass (weight) of the ejecta and the velocity of that ejecta as it departs the confines of the barrel. There is no transfer of the pressure forces outside of the chamber except for the expulsion of the ejecta. It is the force of recoil that causes the mechanical actions (back thrust, torquing of the frame, deflection of the barrels and transfer of force from the barrels through the frame to the stock that produce what we are referring to as wear.

OK, mark-up my respones as you see things.

Suppose we weld a solid plug in front of the chamber and the chamber walls and action are strong enough to contain the pressure. On firing, the chambers will experience radial pressure , which is not related to this discussion. The plug will experience forward pressure which will try to move the barrels toward the muzzle and is relevant to this discussion. The fences will experience rearward pressure (thrust) which is relevant to our discussion. Keeping in mind that force equals pressure times area, we can tell how much force is acting in each direction. The forward and backward forces are combined into axial force. Axial force till try to separate the barrels and the action. The hook and hinge pin will absorb most of the axial force and the locking bolts and bites will absorb the force trying to open the action in a rotational direction. The flexures between the hook/pin and bolts/bites will occur. Any grinding wear or battering wear will occur. The only thing that will not be present is recoil as there is no movement of ejecta, hence no recoil force.

Now, take off the barrels and fit a "sled." Have a shooter shoulder the gun's stocked action and have a helper strike the front of the sled with a maul. The gun and shooter will experience a force exactly like recoil without any pressure.

Why are modern guns not shot loose as often as older guns?
1. Better metal in the joints.
2. Better lube.
3. Less frequency of shooting after an extended storage period where the oil applied to the joint has run out.
4. Less firing to date.
5. Bigger, more robust joints.
6. Cleaner powders, wads, and hulls.
7. More rigirous cleaning and lubing.

How do I politely say this?

Bullshit

TB, you're contradicting yourself. Down the line, you talk about pressure acting within the chambers of a shotgun barrel. Of course British and other in the know gunsmiths would tell you that you need to look for a thin spot ANYWHERE along the barrel . . . although they're more dangerous the closer you get to the breech (more pressure . . . even holes in the barrel out at the muzzles--aka ports--won't hurt anything). So, why do you suppose Fox bothered with 4 different weights of barrels--if not to help the heavier guns better withstand the pressure AND the recoil (remember, gun weight offsets recoil) from higher pressure, faster, heavier loads? Why were the Super Fox and the Elsie Long Range Wildfowl made a whole lot heavier--if, again, not to mitigate the effects of pressure and recoil?

But hey, if you want to go ahead and shoot the same shells in a 6 pound double as in an 8 pound double and expect the former to suffer no more harm than the latter . . . blaze away!

Fox separated their barrels into 4 groups by gauge and weight simply so the assemblers would choose barrels of similar weight when striking and joining the barrels.

The Super Fox was a whole different frame size than the standard 12 gauge made heavier to better accomodate the Becker over bored barrels (11 gauge) and manage the increased (you got it half right) recoil generated by the Western 2 3/4 inch Super X and later 3 inch ammunition.

What Miller, Twice Barrel, and I agree on and Larry and Rocketman apparently don't is that a tightly set up American gun of quality can take this pressure and recoil business and forget about it, just about forever, as long as the locking mechanism is kept clean and oiled. There is no way that all of our Parkers, Smiths, and Foxes that are still tight and on face were somehow kept from exposure to heavy loads and volume shooting for eighty to a hundred years. No, they survived heavy loads and volume shooting and will continue to survive. This pressure and recoil is a non issue for owners of good quality, well maintained guns.

Rocketman your contrived examples are so far outside of the normal function and sequence of how a shotgun functions that they really have no bearing on this discussion of what is the genesis of accelerated wear in a shotgun that it has no relevance. Additionally in your rambling responses it appears that you have totally disregarded Newton's laws of motion in all of your reasoning.

A high quality shotgun is designed and built to not flex or expand with any reasonable load. No flex, no expansion, no wear. That's why well maintained shotguns 130-140 years old are tight as new.