Calculating rifle movement as bullet reaches muzzle

[Rat Rifle]

And like I've always said! Rifles are like women some like to be held tight, and some don't.

Joe Salty

Your absolutely correct Joe, but all women prefer more than 1/8” of movement

 

[Dgd6mm]

This thread as now lost my interest.

 

[CharlieNC]

OP you have received numerous opinions about recoil but the bottom line is the manner by it is addressed by stock design, shooting rests, and shooter technique is infinitely more important. Recoil management of a 22lr is just as critical as a 300wm.

 

[BoydAllen]

Let me get this right. You want us to do all the work to answer a question that none of us have a functional reason for wanting to know the answer to? You claim that your visualization of the problem is correct ant those of others are not. Come back when you have done all the simple calculations and have an answer. Then you can post it all and explain it.

 

[Bottom Fodder]

I’m enjoying what all “the smart people” are posting and they are getting to use all that “advanced math“ they got in school that the teacher told them they could use someday. The only Advanced math I use in life was. E=I/R

 

[TaperPin]

Perhaps you need to spend more time in small boats. Back when I did, if I was slow and careful, the boat did not move at all in the opposite direction to the one I was moving in. You carry on about how simple it all is. If it is, do the calculations and post them and your answer. Actually I wrote about the way the pressure curve influences the barrels movement as the bullet goes down it. toward the muzzle, with the total movement just before the bullet clears the crown being the total of how much it moved during each small part of its travel. In other words, since the pressure is non linear, so is anything linked to it.

I did use my junior high math in post #54 and posted how close it was.

Show me where the kid’s velocity had anything to do with center of mass as he is being propelled down the board by his legs:

 

[TaperPin]

OP you have received numerous opinions about recoil but the bottom line is the manner by it is addressed by stock design, shooting rests, and shooter technique is infinitely more important. Recoil management of a 22lr is just as critical as a 300wm.

I agree. I’ve just been curious my entire life about how far a gun recoils before the bullet comes out. Recoil after the bullet leaves the barrel is not going to change the bullet’s path, so it seemed to me, most people would be interested in it - aren’t all accuracy minded shooters interested in it?

 

[Straightshooter1]

I agree. I’ve just been curious my entire life about how far a gun recoils before the bullet comes out. Recoil after the bullet leaves the barrel is not going to change the bullet’s path, so it seemed to me, most people would be interested in it - aren’t all accuracy minded shooters interested in it?

I would think so, to some degree . . . depending on the shooting discipline, just as lock time can be.

 

[CharlieNC]

I agree. I’ve just been curious my entire life about how far a gun recoils before the bullet comes out. Recoil after the bullet leaves the barrel is not going to change the bullet’s path, so it seemed to me, most people would be interested in it - aren’t all accuracy minded shooters interested in it?

It is apparent recoil up to the time the bullet exits drives accuracy, and it is enough to have a dramatic effect if not managed properly by the shooter. The recoil after that is important to those shooting tactical, prs, etc because it is essential to spot your poi in order to make adjustments rapidly on the fly.

 

[TaperPin]

I’ve started to see more tactical shooters thinking about rifle movement as the bullet goes down the barrel, since many are shooting semi rigid bipods. While the bullet is in the barrel, feet of the tripod need to recoil smoothly and consistently at least until the bullet departs. I’m starting to believe the guys who are in favor of preloading the bipod based on their testing have more gun movement (recoil) than those who say they have tested preloading and found no change in accuracy. If a tactical 300 mag moves .25” while 223 moves .025” the shooters should probably know their number to better understand what’s happening, help direct testing efforts and equipment decisions.

I can’t help but think the trend will be towards bench guns having barrels more in line with their center of gravity so there‘s reduced muzzle rise torque - heavier, higher scopes and lighter low profile stocks

 

[TaperPin]

Let me get this right. You want us to do all the work to answer a question that none of us have a functional reason for wanting to know the answer to? You claim that your visualization of the problem is correct ant those of others are not. Come back when you have done all the simple calculations and have an answer. Then you can post it all and explain it.

Do you at least agree that until the bullet leaves the barrel, the rifle is acting as a closed system? If so, do you agree the center of mass doesn’t accelerate until the bullet leaves the barrel?

 

[davidjoe]

Do you at least agree that until the bullet leaves the barrel, the rifle is acting as a closed system? If so, do you agree the center of mass doesn’t accelerate until the bullet leaves the barrel?


View attachment 1502338

I’m watching your process from an old parallel thread, you may have seen it.

Closed system, you say? If captivation to the finer points of accuracy is the Force, we are seemingly viewed as Dark side sensitive.

There are always two.

 

[Varminterror]

The bullet cannot anticipate a vent, and start the system recoiling, before it gets there.

The bullet moving down the bore is - effectively and functionally - the vent. In a sealed pressure vessel, nothing is moving, so the pressure, the force, is net zero because the resistance of the vessel wall is holding back the pressure, the force, therefore there is no acceleration of any part of the system. In other words, “no action.” However, with a dynamic plug - a bullet - in the system, there IS acceleration caused by the force, so the fore and aft forces against the rifle are not balanced. If I put a threaded plug in the muzzle and raised pressure, the force against the plug pressing left would balance the force against the boltface pressing right, and there would be no net force on the rifle. The system is sealed and static. But when we use a bullet instead of a plug, we have an accelerating body being pushed in one direction, and therefore the opposing force - the pressure on the rear of the action - is no longer balanced by that on the front (no plug to push against which would pull on the barrel which pulls on the action which pulls on the bolt and balanced the force on the bolt face in the plugged system). So now we have accelerating bullet forward and accelerating rifle rearward.

This is the most basic principle of high school physics. Super simple stuff. You’re circling the drain here but completely missing the target.

 

[Varminterror]

Do you at least agree that until the bullet leaves the barrel, the rifle is acting as a closed system?

Closed but not static.

If the center of mass of the system is accelerated by the internal force, you HAVE to understand that this means the bullet moves one direction and the rifle moves the other, due to the nature of the system and inherent motion of the components.

 

[Varminterror]

I know I’m driving in the lane less travelled, but, if the bullet came to a sudden stop at the end of the barrel, that’s the only change that would be evident in the closed system, recentering of mass.

The center of mass would not return to the same position relative to the barrel, because the center of mass for the resulting system would no longer be the same as the original state. Unless the bullet perfectly rebounds to its original position, the original center of mass position relative to the barrel will not be regained.

 

[Varminterror]

If I’m so far off base, living in never never land, why then does my method match Quickload to within .0028” of the screenshot in message #48?

As I mentioned previously - you are relying on differential calculus to give you the answer for your time “dimension,” then using that to solve the oversimplified math you’ve presented. It’s “4-2=2,” because “I know 2+2=4”. It really is a trivial analysis. Using barrel time calculated any other means, such as using the barrel length divided by the muzzle velocity, would give an incorrect value for rifle displacement. But QL is using higher order mathematics to determine barrel time - which doesn’t correspond to the muzzle velocity, but rather to the time averaged velocity, compensating for acceleration.

 

[mattri]

I’m enjoying what all “the smart people” are posting and they are getting to use all that “advanced math“ they got in school that the teacher told them they could use someday. The only Advanced math I use in life was. E=I/R

Hey that's not true, don't you bend pipe?

 

[davidjoe]

The bullet moving down the bore is - effectively and functionally - the vent. In a sealed pressure vessel, nothing is moving, so the pressure, the force, is net zero because the resistance of the vessel wall is holding back the pressure, the force, therefore there is no acceleration of any part of the system. In other words, “no action.” However, with a dynamic plug - a bullet - in the system, there IS acceleration caused by the force, so the fore and aft forces against the rifle are not balanced. If I put a threaded plug in the muzzle and raised pressure, the force against the plug pressing left would balance the force against the boltface pressing right, and there would be no net force on the rifle. The system is sealed and static. But when we use a bullet instead of a plug, we have an accelerating body being pushed in one direction, and therefore the opposing force - the pressure on the rear of the action - is no longer balanced by that on the front (no plug to push against which would pull on the barrel which pulls on the action which pulls on the bolt and balanced the force on the bolt face in the plugged system). So now we have accelerating bullet forward and accelerating rifle rearward.

This is the most basic principle of high school physics. Super simple stuff. You’re circling the drain here but completely missing the target.

I’m cognizant you don’t average many posts per year, and exceptions to the reservedness may only be for the most select of contributions. Your points are well taken.

I answered the latter reply before seeing this one, answered it, and deleted the prior one. If I understand your post, you are saying, in essence, it does not matter whether a rifle is a closed system prior to exit, as far as recoil is concerned, the same thing happens. Does a completely plugged barrel, where the bullet never exists, still recoil, such that if judiciously controlled, this method could be used as a ventless type of engine, in zero gravity? Obviously other engines separate and push off from part of their mass, or push off on the road, water, etc. so I’ve wondered what the explanation is for how a plugged barrel, closed system would arguably be able to fire bullets at its plugged other end propel itself. This is a pet query I’ve posed, not new, because of your reply, but I think you might shed more light on the answer to it. Is that answer that it will recoil, but then stop continuing to recoil when the bullet strikes, which is not exactly satisfying because it still means another and another and another bullet could be fired, amounting to the same thing as closed system self propulsion.

Is the bullet moving down the bore a “vent”, or is the pressure vessel as viewed from the pressure center, simply growing at both ends, that originated in the cartridge, exactly between the bullet and the bolt face?

Is this unbalanced system you’re describing dependent on the velocity of the bullet, or only the position of the bullet?

In other words, is the rifle going to end up in the same exact position reward, no matter how fast or slow the bullet gets to the muzzle? I’d liken this question to a space walker that can’t close a 10 foot gap to the craft, as they both move at 25,000 mph. He can flail about, and it will relocate an extremity relative to his core and other extremities, but he cannot move his center of mass closer to the craft absent an outside force influence, he can only change where that point is, in his body, though in space the body is always in balance. Part of my mind thinks a bullet moving down a barrel, while it could yet be contained, is limited to relocating the rest of the rifle by this very slight amount, and not more, at least ultimately. (You can walk the length of Taperpin’s boat diagram and get the other end to slightly move, but it is exceedingly limited and you cannot devise a manner of pacing the craft where that motion allows you and the boat to cross the lake, you must push off of the water, capture the wind, etc.)

edit: I’m going to predict your answer would be velocity dependent, as more velocity equals more recoil, but so does more mass, though how heavy the bullet is does not bear in the imbalance of pressure in the system with a dynamic plug, right?

I’m curious what you’d say is the result of a compressed steel spring being released that slowly forces the bullet to the muzzle, pushing against the bolt.

I’ll think on the dynamic plug; it doesn’t seem so basic to me, but it has been a long time; I did graduate HS, but I’m not volunteering to sit for physics retention examination, these days.

I have been assuming pressure equalizes instantly, so the “no plug to push against” as it recedes from the bolt face is a fresh thought to me. At first blush I’d think yes, the plug to push against is retreating, but the fact that it does so is lowering the pressure throughout, and equally so, because the chamber volume is increasing.

There are other ways that the right (muzzle end) of the pressure could be released, and I’m not sure how the rifle would know the difference, or what the effect would be, such as pressure being contained by a membrane that bursts, a controlled valve or shutter that lets gas escape equivalently, or a plug that is quickly withdrawn from the muzzle end.

Is it really even about a “dynamic plug
to push against and pressure” or is what your saying that a certain mass of bullet moved one way, and therefore the rifle must move the other way, and the same result would obtain if the barrel was a magnet and propelled a bullet to its end?

I have always acknowledged I’m just challenging for the purpose of an explanation the idea, accepted as a law, that the rifle at least absent inertia, wants to start moving when the bullet does, because other closed systems don’t appear to behave in this manner,

I’m not so much trying to refute a natural law as to point out that if we did not call a gun a weapon, but rather an engine, the same natural laws would apply, but now the object seemingly bends or breaks a different law, by allowing recoil (propulsion) to exist when a bullet never leaves the gun, which is pre-exit recoil, analogous to engine thrust when the vent of the engine is completely sealed.

 

[Straightshooter1]

I answered the latter reply before seeing this one.

Is this unbalanced system you’re describing dependent on the velocity of the bullet, or only the position of the bullet?

In other words, is the rifle going to end up in the same exact position reward, no matter how fast or slow the bullet gets to the muzzle?

edit: I’m going to predict your answer would be velocity dependent, as more velocity equals more recoil, but so does more mass, though how heavy the bullet is does not bear in the imbalance of pressure in the system with a dynamic plug, right?

I’m curious what you’d say is the result of a compressed steel spring being released that slowly forces the bullet to the muzzle, pushing against the bolt.

I’ll think on the dynamic plug; it doesn’t seem so basic to me, but it has been a long time; I did graduate HS, but I’m not volunteering to sit for physics retention examination, these days.

I have been assuming pressure equalizes instantly, so the “no plug to push against” as it recedes from the bolt face is a fresh thought to me. At first blush I’d think yes, the plug to push against is retreating, but the fact that it does so is lowering the pressure throughout, and equally so, because the chamber volume is increasing.

There are other ways that the right (muzzle end) of the pressure could be released, and I’m not sure how the rifle would know the difference, or what the effect would be, such as pressure being contained by a membrane that bursts, a controlled valve or shutter that lets gas escape equivalently, or a plug that is quickly withdrawn from the muzzle end.

Is it really even about a “dynamic plug
to push against and pressure” or is what your saying that a certain mass of bullet moved one way, and therefore the rifle must move the other way, and the same result would obtain if the barrel was a magnet and propelled a bullet to its end?

See attached regarding Recoil In Electromagnetic Railguns

 

[JFrank]

The bullet moving down the bore is - effectively and functionally - the vent. In a sealed pressure vessel, nothing is moving, so the pressure, the force, is net zero because the resistance of the vessel wall is holding back the pressure, the force, therefore there is no acceleration of any part of the system. In other words, “no action.” However, with a dynamic plug - a bullet - in the system, there IS acceleration caused by the force, so the fore and aft forces against the rifle are not balanced. If I put a threaded plug in the muzzle and raised pressure, the force against the plug pressing left would balance the force against the boltface pressing right, and there would be no net force on the rifle. The system is sealed and static. But when we use a bullet instead of a plug, we have an accelerating body being pushed in one direction, and therefore the opposing force - the pressure on the rear of the action - is no longer balanced by that on the front (no plug to push against which would pull on the barrel which pulls on the action which pulls on the bolt and balanced the force on the bolt face in the plugged system). So now we have accelerating bullet forward and accelerating rifle rearward.

This is the most basic principle of high school physics. Super simple stuff. You’re circling the drain here but completely missing the target.

I should have stayed in school. Miss one day and look what happens.. Geez

Glad to see you here VT…