Magnum not inherently less accurate?
- Thread starter davidjoe
- Start date
To paraphrase the infamous Vincent Gambino... "Perhaps the laws of physics cease to exist on your (gun)"
The gun/shooter will recoil a distance proportional to their mass in relation to the mass being accelerated in the opposite direction. The more mass of the gun and less mass of the projectile, the less distance the gun will move by a given accelerating force. It may be small but it will move. I think you do understand this, David, as I know you are rather intelligent. I'm not sure exactly what you are questioning.
Once the force is enough for the gun to start moving, it will be proportional.
Supposing 95% of all the elements of recoil are those that come to exist at exit, the nozzle and two masses separating effect, then you just need a gun heavy enough to ride out 5% before it starts moving.
Take a 737 heavy, number one for takeoff, squatted and still from well fed turkey day passengers.
Those engines, like starship heavy, are going to eject material doing what they do, for a measurable time, before the plane/rocket move any distance.
overcoming resting inertia must happen first.
It’s not that hard to do with a rifle, finding a weight / cartridge where the bullet is gone by the time resting inertia is overcome.
But it may not even be 95 /5% recoil after and before exit.
What I’m suggesting is that physics principles in other examples do suggest that all recoil in the rifle, is post bullet exit. If it was all post exit, then it (recoil) won’t make the gun less accurate, shooting a magnum, because the bullet is gone when the rifle moves back. This is not to say recoil is the only factor. But, we are simply considering it.
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If the force is enough to cause the bullet to move, the gun will be moving in a vector opposite to the bullet as soon as the bullet moves (ignoring the little understood 'force' of stiction between the rifle and rests). 'Overcoming inertia' must also include both masses you are considering. Both masses will be subject to accelerating forces and both will move accordingly, no matter how minute the movement.
Of course, no matter how intellectually stimulating such discussions are, this is like dissecting a butterfly to find out why it is so beautiful. You end up with a bunch of pieces instead of just appreciating beauty it possesses. Funny how these theoretical discussions always pop up in winter.
SteveOak
Gold $$ Contributor
So the discussion is now recoil effect and not inherent accuracy.
If the force is enough to cause the bullet to move, the gun will be moving in a vector opposite to the bullet as soon as the bullet moves (ignoring the little understood 'force' of stiction between the rifle and rests). 'Overcoming inertia' must also include both masses you are considering. Both masses will be subject to accelerating forces and both will move accordingly, no matter how minute the movement.
Of course, no matter how intellectually stimulating such discussions are, this is like dissecting a butterfly to find out why it is so beautiful. You end up with a bunch of pieces instead of just appreciating beauty it possesses. Funny how these theoretical discussions always pop up in winter.
Agree the gun will feel the same amount of force the bullet does, as the bullet starts moving.
I calculated that an F-Open gun is 855 times the weight of a Berger 180. 7000 times 22 / divided by 180.
So, just looking at that, on a rest and shouldered, ( disregarding some side issues I analogized to on theory) it may or may not be possible have the bullet completely exit prior to the rifle moving back, but I think if a guy put a 90 pound gun on the line, it would absolutely be gone before the gun moved.
I’ll try again, it’s about inherent accuracy as a function of the effects of recoil (which can only degrade and never improve accuracy), while recoil could still affect the bullet, (still within the barrel).
Other things like a magnum damaging the jacket, overheating the barrel to walk the shots, or distracting the shooter, from its recoil haven’t really been discussed.
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BoydAllen
Gold $$ Contributor
In another thread I posted a high frame rate video that shows that the rifle, a magnum, moved before the bullet exit, which proves a couple of things, that it moved before the bullet exited, and that your visualization of the problem and application of physics is incorrect. I also gave a couple of examples in other posts that prove the same thing. Here is another video.
You think that your (note: THERE WAS A TYPO IN THE ORIGINAL POST THAT I CHANGED FROM VIDEOS TO VISUALIZATIONS) have some probative value. They do not.
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The post earlier about the Lapua and Eley machine rests at the test centers, though… they totally prevent movement and simply make the steel absorb the recoil…. and overcoming resting inertia….
Years back when resting inertia was cited in the same three laws, guys agreed.
There are videos I’ve seen that show both movement, and no pre exit movement, only post exit movement. Very high resolution too.
I’ll fully assume that in this video, they tried to pull the trigger without moving the gun back and succeeded. I’ll assume it’s a heavy gun, but it’s not like ours.
I’m not certain I’m right about no recoil pre-exit, but even the authorities writing on the subject say most of recoil is the nozzle and the separation effect.
We know from your video above, that in front of that bullet is an invisible column of air, that the bullet accelerated to 3000 fps. I believe the bullet is fairly firmly gripped by the barrel and wants to stop if the pressure behind it does, but that air is not.
Pushing that air forward, inarguably pushes the gun back at least some amount, and this isn’t the recoil the laws of physics are talking about.
If we “shot” that magnum rifle with the same volume of compressed air, could we expect it to move a 1/3 of a matchstick’s width, which is what it does pre exit?
… second reply to this one, what if the bullet was being pulled out of the neck and forward, by its nose? Similarly, how does the gun know that the bullet Is not moving forward because I’ve got the bolt out, and I’m tapping the rear of it with a rod and mallet?
Powder exploding may lend a mystique to what we do that inhibits certainty.
If the bullet didn’t leave the neck and move to the muzzle because of powder, but rather because a long steel spring had been released, and that spring was just a tad shorter than the barrel, and we “fire” this gun, such that the bullet stops at the muzzle because the spring is too weak/short, then, in this scenario, does the rifle still recoil? If not, why, because the bullet did move.
If there is movement, which I’d expect to be small, is it “recoil” or is this simply finding a new “center”?
I have referenced above that a grandfather clock on ball bearings will counter its own pendulum with slight movements, until it stops, attempting to recenter itself.
If functionally, a spring and powder are the same, then we should analyze them the same way, right?
If the bullet didn’t leave the neck and move to the muzzle because of powder, but rather because a long steel spring had been released, and that spring was just a tad shorter than the barrel, and we “fire” this gun, such that the bullet stops at the muzzle because the spring is too weak/short, then, in this scenario, does the rifle still recoil? If not, why, because the bullet did move.
If there is movement, which I’d expect to be small, is it “recoil” or is this simply finding a new “center”?
I have referenced above that a grandfather clock on ball bearings will counter its own pendulum with slight movements, until it stops, attempting to recenter itself.
If functionally, a spring and powder are the same, then we should analyze them the same way, right?
BoydAllen
Gold $$ Contributor
In his book, Rifle Accuracy Facts Harold Vaugn presented a lot of material about factors affecting the integrity of the barrel action joint, quite a bit of which relates directly to the original question posed in the title of this thread. While used copies are pricey, the entire book is available on line, for free.
I bought a copy back when the book was first published, and spoke with the author a couple of times. For those who are interested in taking a close look at some details that have not shown up in print in other places, I recommend that you read the entire book.
Added Later: The Cliff's Notes version of this topic is that with enough pressure, and relating to the working cross section of the tenon, the tenon stretch unloads the joint where the action face meets the barrel shoulder, allowing for movement between them, negatively impacting accuracy. It has bee a couple of decades since I read this, but I am pretty solid that I have the gist of it correct.
Rifle Accuracy Facts Full V 1.0 ( First Full Scan) : Harold R. Vaughn : Free Download, Borrow, and Streaming : Internet Archive
The author, who spent his career studying trajectories of nuclear missles and artillery shells, wrote this work after becoming dissatisfied with the accuracy...
archive.org
Added Later: The Cliff's Notes version of this topic is that with enough pressure, and relating to the working cross section of the tenon, the tenon stretch unloads the joint where the action face meets the barrel shoulder, allowing for movement between them, negatively impacting accuracy. It has bee a couple of decades since I read this, but I am pretty solid that I have the gist of it correct.
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I think that was a good point. No doubt, the air being pushed and accelerated forward in front of the projectile has some effect on that overall recoil. But I have doubts that its effect on recoil before the projectile leaves the muzzle is anywhere as great at the force the accelerating projectile is producing. By the time the projectile reaches the end of the bore, I suggest that its "mass" grows to quite a bit more than that of the total mass of the gun, if only for a very short time before it exits resulting in that small amount of recoil.
I no longer am math capable of doing the calculation for the mass. I am curious as to what the mass of a 200 gr projectile is traveling at 3000 fps.
Just my thought for the day.
BoydAllen
Gold $$ Contributor
I believe the mass is still 200 grains. Here is a link to a page that will calculate momentum and energy from weight and velocity.I think that was a good point. No doubt, the air being pushed and accelerated forward in front of the projectile has some effect on that overall recoil. But I have doubts that its effect on recoil before the projectile leaves the muzzle is anywhere as great at the force the accelerating projectile is producing. By the time the projectile reaches the end of the bore, I suggest that its "mass" grows to quite a bit more than that of the total mass of the gun, if only for a very short time before it exits resulting in that small amount of recoil.
I no longer am math capable of doing the calculation for the mass. I am curious as to what the mass of a 200 gr projectile is traveling at 3000 fps.
Just my thought for the day.
Shooter's Reference Energy, Momentum, Power Factor, and Taylor Knock-out Calculators
Good thought. To me, it’s along these lines of thinking.
Sometime about 2014 or ‘15-ish, Berger started shipping the 195’s which had been announced and in development for a couple of years, or nearly that.
When they shipped, basically everyone who gave them any thought, believed that you really needed to shoot them from a magnum, if trying them in F-Class.
The thought was they are too much for a .284. I picked RE 25 and shot them out of a .284, anyway, and they were better for me than 180’s had been.
My working definition would be:
When two different options are both optimized, and neither has been pushed outside reasonable parameters, is one simply better shooting than the other, by being inherently more/less accurate?
Say we are following Litz’ advice, picking our bullet first, and going from there, then in that case some examples of this concept to me would be:
1) a lighter rifle, same cartridge, is inherently less accurate than one allowed to be built heavier;
2) a thinner contoured barrel is less capable of aggregating in matches than a thicker barrel;
3) filling the case with volumetric charges is less accurate in LR than weighed charges;
4) blunting the tips of that box of bullets versus how they came, will never improve them, while making them pointier, might;
5) a larger case choice, in capped rifle weight, than is required where you could still make the correct wind call, is less accurate.
Things like this. Number 5 would be closest to the subject of this thread.
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That’s kinda my point. “Inherent accuracy” gets thrown around often but it’s all subjective. Similar to “over bore”.
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