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To 'measure' recoil you will need to suspend the firearm from supports that will let it swing and know the weight of the gun and then measure the actual displacement during firing.


To 'measure' presure, you will need a transducer that is calibrated in a chamber connected to a recording device.

'Measurement' is not calculation which I believe you are discussing, PeteM.

To calculate recoil, the mass of the charge has no bearing and is not included if indeed it is calculable.
To calculate pressure, "the plasticity of the barrel" has no bearing and is not included.

It is not simple Physics. -Dick

You're talking about blowing up a barrel because of a stuck wad?
I've never had the pleasure. However, the answer to your hypothetical would be there would be little or no recoil because the ejecta never achieved any velocity, to speak of. You might need some clean shorts but not because of recoil.
You can have many times the allowable pressure and blow the gun to smithereens, while having no recoil at all. No ejecta velocity = no recoil. Further proof that pressure has nothing to do with recoil.

I think what PeteM is trying to state, which would be getting back to first principles and a simple approach, is that the sum of the Forces equals Zero(F(total) = 0). An increase of transverse forces could be attenuated or dampened by the strength of the tube while an increase in longitudinal down barrel(Fb+) force due to a higher velocity would be subject to a higher negative/reverse force depending on the friction factor(like a -kx spring factor) down the tube.

Also I failed to note that due to the geometry of the tube and if the tube is concentric the reflected/attenuated wave/vector collides with another reflected/attenuated wave at the center of the tube and cancels each other similar to a standing wave. If one of the transverse waves isn't reflected or only partially reflected from a weakened portion of the tube then the weakened portion experiences the opposite reflected wave which was to be cancelled.

Kind Regards,

Raimey
rse

Couple of notes. Total recoil is easily calculated from gun weight, ejecta weight, and ejecta average velocity via conservation of momentum and the relationship of kenetic energy to weight and velocity. Note that there is no pressure term. Now, felt recoil is not understood well enough to be defined. It could involve rearward force, rearward acceleration, or rearward velocity. Pressure acts over the area of the base of the wad and becomes force. The force from the pressure is unbalanced and results in acceleration of the payload. The acceleration results in velocity. As physics goes, that is pretty straight forward.

I am not aware of any data that correlates any of the above to felt recoil other than total recoil. Some people could conceivably feel components of the total recoil, but that is yet to be proven.

Pressire in an enclosed vessel has no recoil. So, pressure has influence on recoil only as it relates to rearward force, acceleration, or velocity.

If the barrel were plugged immediately ahead of the chamber, I doubt that normal powder charges could generate sufficient pressure for a chamber burst. An obstruction burst is a whole different phenom. It is caused when the high velocity gas behind the payload is forced to slow down as the payload strikes the obstruction and has to accelerate said obstruction to payload velocity. The gas slowdown results in a very high localized pressure known as a gas hammer. A gas hammer will, indeed, burst a barrel. A barrel burst is going to be violent on a loaclized level, but there will be no increase in recoil. Actually, recoil will be reduced unless the payload is alread at, or near, muzzle velocity.

I don't understand the "Note there is not pressure term" phrase. Pressure has to be a component as pressure is from the force of the expanding gas on a finite area at a static point in time(otherwise time varying because the volume is increasing)and is what starts it all. It's in there somewhere and I would say the effect of the bounding/excited molecules(kg) with a velocity(m/s^w)acting upon the finite area(m^2)of the base of the wad would give a force(N=kg m/s^2) but I don't have my units correct just yet.

Kind Regards,

Raimey

rse

I would be most concerned about compressing the shot in the column, by forcing it through a narrowed opening and therefore distorting it, would wind up blowing the pattern. I know for a fact, that lengthening the forcing cone improves patterns, so it only stands to reason the opposite would hurt.

binko

Two points: If the shot load hits an immovable obstruction in the bore there should be movement off the shoulder as the inertia of the moving load should be pushing the gun forward. However I doubt anyone notices it just as the barrel rips open.

Second point is if pressure itself produces recoil as Chuck believes then he should be able to also feel the barrels moving upward and downward at the same time in his hand as the pressure is acting with equal force in all directions. And with more surface area of the barrel sides involved than the area of the standing breech, he should feel more of this recoil in his forward hand than his shoulder.

I will stick with the law of physics and continue to believe recoil is a function of velocity produced.

REVDOCDrew I don't discount your antedotal incident. However, you need to compare equal velocity loads in both lengths (and blind so you don't know which is being fired) before the test would have any significance.

Don,
I am not aware of any data specific to that either. As far as being able to feel anything other than total energy from the recoil, I would say that I believe I can. That has yet to be proven though...conversely, it has yet to be disproven as well.

Jerry,
I believe you have misrepresented what I stated. I stated that it was a key component in producing recoil. That might seem subtle to you, but is a huge difference to how I would interpret the statement. I can't imagine how you'd make recoil in a gun without pressure, nor the other components I mentioned either. I believe they are inseparable in the real world.

What would you expect other than brutal recoil when shooting a 20 ga. gun weighing less than 6 pounds? Chopperlump