When showing off your new Elephant rifle goes wrong

ER doctor here….no excuses for alcohol consumption commingling with firearms usage. Ever. With kids around? Don’t get me started…At best stupid boorish behavior. At worst a case for department of Child Welfare. My youngest GSW case this week was 14…
and we wonder why Double Gun Journal is folding. We didn’t teach our kids responsible firearms behavior and just give ammo to the anti’s. No pun intended.
If I wore a tin hat I would have thought this was a false flag post. Sadly it doesn’t appear to be. Just like a post on another forum where the THC vapers in a local gun club demanded their right to puff on the firing line like tobacco smokers..
what the actual bloody hell???
 
Hey Alistair, Thanks for reminding me why I never took physics in school. Chasing girls was so much more fulfilling.
It's fair to say that my performance in that class dropped sharply when I realised that boobs are interesting...
 
Soon after I took delivery of my Krieghoff Teck O/U DR in .458 WM, I had it out on the farm wandering around looking for targets of opportunity. I decided to shoot at a knob on a tree roughly 50 feet away and proceeded to line up the sights of the 2 1/2X scope and squeeze a shot off. What followed was an enormous boom and I found myself relentlessly propelled rearward, I took two steps backwards and got my feet tangled up and sat down. The event was a genuine double, since the two bullets impacted only inches away from each other, and I took the rifle in to my gunsmith to have whatever was wrong corrected. Whatever he did, did the job, since that was in 1971 and the rifle has accompanied me on three African hunts, with a total of eleven weeks in the field, with no further difficulties.
For those technically inclined, the recoil of such a "double" is four times that of a single shot, since the recoil varies with the square of the bullet weight and since the bullet weight is doubled, the recoil is quadrupled. Nonetheless, I suffered no injury, except perhaps to my pride, no broken bones or even bruises. I didn't have a similar experience again until I tried out my .577 bolt gun, but I managed not to get my feet tangled up and remained standing after retreating two paces after firing it.
I was incredulous but then I calculated the recoil with one bullet and then with two, (You have to double the powder charge as well, not just the bullet weight), the results came to precisely 4 times the recoil of a single tube. So, you're absolutely correct !!
Glad you weren't transposed into another zip code.
 
Just when I though the thread would die and not make 12 pages.

Anyway Saturday Safari Outdoor the biggest gunshop in South Africa held DGS shoot one of my mates made the mistake to not properly hold his grip on his 470 Krieghoff and had a double disharge but actually hit the target twice. Normally that second bullet is way high over target.
 
Not intuitive indeed.

In fact, the energy doubles, but the recoil velocity increases by a factor of sqrt2 (1.4ish).

E=1/2mv^2.

E forwards = E backwards (conservation of energy).

1 bullet energy forwards (simplified figures for demonstration, bullet mass = 1, velocity = 2.).

E = (0.5)(1)((2)^2)) = 2

2 bullets energy forwards.

E = (0.5)(2)((2)^2)) = 4

This makes logical sense. You burnt twice as much powder and sent twice the projectile weight downrange at the same velocity.

Recoil velocity. Rifle mass = 10 for ease of calculation. E values bolded.

Rearranging the energy equation for v.

E=1/2mv^2
2E = mv^2
2E/m = v^2
Sqrt(2E/m) = v

1 bullet.

sqrt(2(2)/(10)) = v. v = 0.632

2 bullets

sqrt(2(4)/(10)) = v. v = 0.894

QED. That's what the calculator is doing also.

Unless you can magically create energy from nothing, that has to be the case. There's no way to double the recoil velocity without quadrupling the energy and that simply didn't happen. How can it? You've only burnt twice as much powder and chucked two bullets down range at the same velocity as you previously chucked one. 2x energy, not 4x.
I really tried to resist the temptation to respond and couldn't. :giggle: My apologies to the non-physics types out there.

Sorry Alistair, I have to disagree with you. Your starting assumption is flawed - this is NOT a conservation of energy problem (remember there is heat energy involved, the kinetic energy retained by the bullets flying off into the ether etc which you have not accounted for.)

As I stated before, this is a conservation of momentum problem and there is the impulse effect. Impulse is defined as being a force that is being applied for a period of time. This is in essence what you have proved - that the recoil impulse doubles with a simultaneous discharge.

Force = mass times acceleration (F= m * a)
To cut to the chase, with the simultaneous discharge, the force must be double because the mass has doubled (two bullets and two powder charges). Acceleration has stayed the same for the bullets & powder going down the barrel.

For the rifle, the mass has stayed the same but it experience the equal and opposite reaction (conservation of momentum) so it experiences twice the force of a single discharge.
Therefore the rifle must experience twice the acceleration because if force has doubled and mass is constant, then solving for the remaining variable (acceleration) tells us this.

Acceleration is the rate of change of velocity (i.e. the difference between the velocity when the trigger is pulled, which was zero. And the velocity when the bullet leaves the barrel).
We've assumed the time of this event (bullets travelling down the barrel is the same in both cases - same muzzle velocity whether 1 bullet or 2)
The starting velocity in both cases is zero.
Therefore the terminal velocity of the rifle in the double discharge case has to be double the terminal velocity of the single discharge.

If the rifle velocity has only increased by a factor of 1.41 as you've suggested, how do you get to double the force (which I believe is common cause in this scenario) seeing as your acceleration has only increased by 1.41 and not by 2?

I've tried not to go into the long-winded maths proof of this but I assure you it holds true.
 
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And to help us get closer to 12 pages, I had a quick browse of the 'net:

https://shooterscalculator.com/recoil-calculator.php

https://www.omnicalculator.com/physics/recoil-energy

https://bisonballistics.com/calculators/recoil

Even those with a dislike of physics should be able to use these calculators easily and see what they spit out.
Do you get 4 times recoil energy or 2 times when you double the bullet and powder mass, and keep velocities and rifle mass the same?
You get 4 times (four) the recoil.
 
I’m not a physics guy, just a common sense guy.

There are many kinds of doubling that can occur. The most famous i think was Pondoro that wired his triggers together for a double hit? Yep, that would be maximum recoil scenario but impossible to actually calculate that recoil, sorry math guys. The reason you cannot is you can’t quite predict the amount of rearward recoil by the fact that one barrel is providing left lateral recoil and the other is providing right lateral recoil. We also cannot figure out how many milliseconds later the second shot is occurring and therefore how much the rifle is already moving for the recoil to act upon rather than by acting on a static weapon.

Then we go to normal doubling, as in when the gun is shot twice with a reasonable interval between the two shots. Tenth of a second? Fifth of a second? Nearly a second? We can’t really calculate this one either because the variable is an object in motion (from the first recoil) tends to stay in motion, so the second shot will have a greater enhancement to rearward recoil than the first shot because the gun already has momentum.

You can’t take recoil of first shot x2 as a formula. Nor can you square them. Nor can you even predict if the recoil pad is already met full resistance and is already providing forward counter recoil when the second shot goes off in which case the second shot may have less recoil than a stationary gun because it must first counter the forward recoil of the first shot recovery to initiate the second shot’s rearward recoil.

Sorry to ruin the fun with math and physics, but there are infinite variables and the time intervals between the shots and their ignition, even the powder burn rates, all would make this way too confusing to figure out.

Rough math guesstimate, if a first shot’s effective recoil is 70lbs a doubling could be anywhere from 70lbs to >140lbs.
 
You can’t take recoil of first shot x2 as a formula.

Sorry to ruin the fun with math and physics, but there are infinite variables and the time intervals between the shots and their ignition, even the powder burn rates, all would make this way too confusing to figure out.
Yes you can - there is a clearly stated assumption of simultaneous double discharge. I accept that true simultaneous discharges are not the norm and if there is a lag there's a bunch of other stuff to consider.

You will see terms like free recoil used - this is an assumption because the rifle doesn't have free recoil, it has your shoulder providing resistance. Etc. That's why there are some basic assumptions to get the gist of what is going on.
The debate was whether the recoil energy, as defined, was double or quadruple if a double rifle had a true simultaneous discharge.

You're not ruining the fun - this is a solvable problem with some simplifications. A lack of understanding doesn't make something unsolvable. Sure it's complex. The physics principles have been established and understood for a few hundred years, even if this forum is the exception :ROFLMAO:

Anyway, I think there's a categorical answer - even if people think their 'common sense' views might be different, so I'll tap out now
 
The likelihood of both barrels discharging at the same instant in time is astronomical, even if a shooter tries to pull both triggers at the same time! High speed video would reveal this.

What is probable is what seems as a simultaneous discharge to the shooter or nearby humans is in fact the second barrel discharging immediately after the first because of either 1) Human error touching the back/other trigger during recoil of the first barrel, or 2) Mechanical error of the second barrel/action sear disengaging from the trigger as a result of the recoil of the first barrel.

The result would be the rifle giving the shooter two near simultaneous 70 pound recoil impulses into his shoulder. The total would be 140 lbs of recoil over a longer DURATION than firing only one barrel.

The second 70 lb impulse would occur when the shooter's shoulder/body were compromised from the recoil or the first barrel. Not a pleasant experience! In common terms, the back to back double 70 pounds of recoil would nearly knock the 200 pound shooter on his butt!
 
Yes you can - there is a clearly stated assumption of simultaneous double discharge. I accept that true simultaneous discharges are not the norm and if there is a lag there's a bunch of other stuff to consider.

You will see terms like free recoil used - this is an assumption because the rifle doesn't have free recoil, it has your shoulder providing resistance. Etc. That's why there are some basic assumptions to get the gist of what is going on.
The debate was whether the recoil energy, as defined, was double or quadruple if a double rifle had a true simultaneous discharge.

You're not ruining the fun - this is a solvable problem with some simplifications. A lack of understanding doesn't make something unsolvable. Sure it's complex. The physics principles have been established and understood for a few hundred years, even if this forum is the exception :ROFLMAO:

Anyway, I think there's a categorical answer - even if people think their 'common sense' views might be different, so I'll tap out now

In your assumption, a straw man argument that has never occurred in the history of the world (a perfect, simultaneous, zero latency, double discharge) then the math is very simple.

Double the energy in, divide by weight of gun. Momentum would be altered because in your scenario the gun is stationary. Opposing forces of left and right recoil in a SxS are perfectly negated.

Anyone able to do the math on that one? Say 470NE with 106gr of powder to achieve 2150fps to move a 500gr bullet, squared (two shots), divided into the weight of the gun which should be 11lbs. Instead of about 75lbs of recoil you'd get what?
 
I’m not a physics guy, just a common sense guy.

There are many kinds of doubling that can occur. The most famous i think was Pondoro that wired his triggers together for a double hit? Yep, that would be maximum recoil scenario but impossible to actually calculate that recoil, sorry math guys. The reason you cannot is you can’t quite predict the amount of rearward recoil by the fact that one barrel is providing left lateral recoil and the other is providing right lateral recoil. We also cannot figure out how many milliseconds later the second shot is occurring and therefore how much the rifle is already moving for the recoil to act upon rather than by acting on a static weapon.

Then we go to normal doubling, as in when the gun is shot twice with a reasonable interval between the two shots. Tenth of a second? Fifth of a second? Nearly a second? We can’t really calculate this one either because the variable is an object in motion (from the first recoil) tends to stay in motion, so the second shot will have a greater enhancement to rearward recoil than the first shot because the gun already has momentum.

You can’t take recoil of first shot x2 as a formula. Nor can you square them. Nor can you even predict if the recoil pad is already met full resistance and is already providing forward counter recoil when the second shot goes off in which case the second shot may have less recoil than a stationary gun because it must first counter the forward recoil of the first shot recovery to initiate the second shot’s rearward recoil.

Sorry to ruin the fun with math and physics, but there are infinite variables and the time intervals between the shots and their ignition, even the powder burn rates, all would make this way too confusing to figure out.

Rough math guesstimate, if a first shot’s effective recoil is 70lbs a doubling could be anywhere from 70lbs to >140lbs.
No one is talking about a time interval between shots which would amount to two successive shots of a single barrel recoil making this entire conversation moot. Introducing a possibility that no one missed isn't common sense.

I am not a teacher and don't have the patience to go back and forth to refute fallacies !!!

Common sense is knowing what side of a fence to stand on when a bull wants to pass.
It is FOUR times if the two shots are fired at the same time.
 
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No one is talking about the time interval between the shots which would amount to two successive shots of a single barrel recoil making this entire conversation moot. Introducing a possibility that no one missed isn't common sense.

I am not a teacher and don't have the patience to go back and forth to refute fallacies !!!

Common sense is knowing what side of a fence to stand on when a bull wants to pass.
It is FOUR times if the two shots are fired at the same time.

I haven't run the math, but some of the input has doubled, the resistance (Weight of gun) has not doubled.

How would you do the formula? We can't just take the weight of bullet, weight of powder, and velocity as an input because there are two shots. Nor can we double the bullets, powder, and velocity, because the velocities have not doubled.

Asking the question because it doesn't make sense that it would just be a flat 4x as there are 6 elements to the formula even with a normal firing to determine felt recoil.

Screen Shot 2022-09-11 at 1.14.30 PM.png
 
I haven't run the math, but some of the input has doubled, the resistance (Weight of gun) has not doubled.

How would you do the formula? We can't just take the weight of bullet, weight of powder, and velocity as an input because there are two shots. Nor can we double the bullets, powder, and velocity, because the velocities have not doubled.

Asking the question because it doesn't make sense that it would just be a flat 4x as there are 6 elements to the formula even with a normal firing to determine felt recoil.

View attachment 488687
why haven't you done the math before talking "common sense" ? I told you I'm not a teacher, much less with obstinate people. Consult a ballistician. Good luck.
 
why haven't you done the math before talking "common sense" ? I told you I'm not a teacher, much less with obstinate people. Consult a ballistician. Good luck.

Because I stated there were too many variables as no such thing occurs as a true "doubling". The response was effectively, "for simplicity's sake lets assume this thing that has never happened is the straw man. Then the answer is 4x." I don't understand how that can be and I can't figure out how you'd even model the formula to figure out the inputs.
 
Because I stated there were too many variables as no such thing occurs as a true "doubling"
100% correct!

I have participated in research and development tests where we had to fire weapons at precise amount of milliseconds between shots. A fire control system using computer controlled mechanical actuators would fire the machine mounted weapons. These shots where filmed at 10,000 frames per second and higher video. Despite a room full of electrical and mechanical engineers, we had to "dial in" the timing for the exact delay by observing the delay between shots. There are a lot of variables for this.

Obtaining a double discharge where both barrels reached peak pressure at the same time is difficult in a laboratory, and darn near impossible in the field.
 
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