What Does This Change In Impact Point Mean?

THIS IS NOT PROOF. There can be NO CONLCUSION drawn from this or any math done at this point without MUCH more empirical data and testing under MUCH MORE controlled conditions(a freehand has a LOT of potential movement). And then after all of that, it MUST be repeated in order to draw those conclusions. Unless anyone of you here are professional physicists I'm sure there are many more variables (such as the escaping gas from the unsealed chamber) at play here. I've NEVER said it was impossible, but only that THIS experiment PROVES nothing. And certainly doesn't overrule every book I've read saying that recoil has no effect on accuracy. Sounds like people are just looking for ANOTHER excuse for poor marksmanship...."It's not the gun, it's the jerk behind the trigger". So break out your slide rules and carry on.

I can only assume whoever wrote your books had neither a high speed camera or a physics text book.

Go to YT and watch a few HIGHER speed camera's in action...albeit with semi auto's and rifles. No revolvers. Bullets are well down range before noticeable barrel movement enough to affect accuracy in any way shape or form.

I have and your incorrect, physics does not stop working just because the gun is bigger or longer. On a rifle the movement is very small because it has a large moment of inertia around its center of gravity. On a semi auto handgun the slide and barrel are uncoupled from the frame except for the recoil spring until the barrel hits the caming surface. That greatly reduces but does not eliminate the amount of rotation because the slide is allowed to recoil backwards on its rail before it needs to also move the frame.

I asked you earlier to do the math on how much muzzle rise is required to move the bore axis an inch at 100 yards. The answer for a 20” barrel is the muzzle would need to rise 5.5 thousandths of an inch relative to the breech.

I should probably be doing more shooting and less typing....I have loads to work up for a few rifles, play with a new "Labradar" and no I won't be concerned with recoil so that's all which matters to me in the practical world of accuracy. You guys continue to do math...I'll continue to put rounds down range. Accurately. And without fear of recoil induced barrel rise! Cheers!

The OP said he had a modest charge in his hand loads that when compared , did not impact the same vertical poi as a load with a different powder and bullet.
Pretty simple to understand..how bout you Dale ?

Dale Alan said:

Different bullet,different powder,different POI. It's that simple .

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DMW1116 said:

You actually did say it was impossible by saying bullets are NOT impacted by recoil in you’re first post in the thread.

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Because I've never seen/experienced it or even heard/read of anyone professing to experience it either. NOTHING is technically impossible I suppose, but this is very, very close. The only way I can see it being a factor would be in a very low velocity round in a very long dwell time and that would be with a revolver where gas is escaping the forcing cone causing bi lateral movement perpendicular to the shooting vector....but even that I have serious doubts. Until I see a real "study", again, I'll still remain unconvinced. So this is all simply verbal ping pong....what's the point?

DMW1116 said:

So what would constitute a real study you would find acceptable?

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A study which takes all human interaction away from the pistol. So at a mechanically braced rest, with a HIGH speed camera and accelerometer to actually MEASURE the recoil forces and at what point they're induced to the point of altering the path of the projectile. So in other words, a very controlled environment. No wind, no human interaction. And of course it would need to be proved through repeated similar results. No "one off" testing...If you're going to be going contrary to long established shooting dogma, you better have more than a video and some basic physics involved.

CryptKeeper5 said:

Because I've never seen/experienced it or even heard/read of anyone professing to experience it either. NOTHING is technically impossible I suppose, but this is very, very close. The only way I can see it being a factor would be in a very low velocity round in a very long dwell time and that would be with a revolver where gas is escaping the forcing cone causing bi lateral movement perpendicular to the shooting vector....but even that I have serious doubts. Until I see a real "study", again, I'll still remain unconvinced. So this is all simply verbal ping pong....what's the point?

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Nobody has ever perceived the gravitational pull of the moon going over their head either but that doesn't mean it doesn't exist.

DMW1116 said:

Would a Ransom rest be sufficient for a handgun? They allow backward movement. However you have to have backward movement to see how the barrel moves. .

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Yep that's the type of brace I was thinking of but couldn't remember the name. The idea is to take as much of the human element out as possible. Along with a >25k FPS camera shooting along the lateral view of the muzzle in order to see the best shot of the exiting projectile.

Dale Alan said:

Different bullet,different powder,different POI. It's that simple .

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I've got a funny/sad story about this.

A few weeks a go a co-worker asked me if I could help his brother sight mount a scope and sight in his AR15. Usually this is my least favorite thing to do, because I often get requests due to having my own range etc. and I've been able to see a lot of "average shooters" shoot. But I agreed and he and his brother came out:

Mounting scope..zero issues
Bore-sighting..no problem
Confirm at 25 meters..not too bad of groups, not great, but at lest it's a group.
Go back to 100 yards..3-5 MOA at best, we got it sort of zero'd.

Tried 200 meters on a steel plate, everywhere but on steel. Back to 100 and 5 MOA again, slightly different POI. So I checked the scope, checked the mounting all is "OK". Now I'm perplexed so I say to the brother: "Beats me, the only time I've seen something like this is with different ammo". He gets this look on his face...then I pick up some of the fired brass..all different head-stamps, at least 4 different makes. Some commercial, some military. I ask IF it's "remanufactured" (hoping that it's at least the same powder, charge, and bullet). "Nope, it's all factory new. He had loaded about five 30 rounders with all different ammo.

I should have checked.

We then proceed to put half a mag together of the same manufacturer and zero the gun.

Chuck R. said:

I've got a funny/sad story about this.

A few weeks a go a co-worker asked me if I could help his brother sight mount a scope and sight in his AR15. Usually this is my least favorite thing to do, because I often get requests due to having my own range etc. and I've been able to see a lot of "average shooters" shoot. But I agreed and he and his brother come out:

Mounting scope..zero issues
Bore-sighting..no problem
Confirm at 25 meters..not too bad of groups, not great, but at lest it's a group.
Go back to 100 yards..3-5 MOA at best, we got it sort of zero'd.

Tried 200 meters on a steel plate, everywhere but on steel. Back to 100 and 5 MOA again, slightly different POI. So I checked the scope, checked the mounting all is "OK". Now I'm perplexed so I say to the brother: "Beats me, the only time I've seen something like this is with different ammo". He gets this look on his face...then I pick up some of the fired brass..all different head-stamps, at least 4 different makes. Some commercial, some military. I ask IF it's "remanufactured" (hoping that it's at least the same powder, charge, and bullet). "Nope, it's all factory new. He had loaded about five 30 rounders with all different ammo.

I should have checked.

We then proceed to put half a mag together of the same manufacturer and zero the gun.

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Lol, that’s a good one

someguy2800 said:

Nobody has ever perceived the gravitational pull of the moon going over their head either but that doesn't mean it doesn't exist.

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Discounting it's effect on ocean tides of course....

DMW1116 said:

Since I started this thread I guess I should reply.

The question is does recoil affect a bullets path. That is a yes/no question. The answer from both the video and generally known physics laws is yes.

If the question is how much does recoil affect bullet path, that requires a lot more rigorous experimenting and/or some pretty involved calculation.

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The math is the easy part. You stated 1 1/2" difference in the poi between 2 bullets/loads. I keep saying 6/1000". I didn't pull that # out of thin air.

There's no vertical movement from the gas operated slide(it starts to move as the gas is ejected from the case, so before the bullet reaches the muzzle) from what I see. An infinitesimal rearward movement as the bullet is escaping but nothing to affect accuracy in any noticeable way.

CryptKeeper5 said:

There's no vertical movement from the gas operated slide(it starts to move as the gas is ejected from the case, so before the bullet reaches the muzzle) from what I see. An infinitesimal rearward movement as the bullet is escaping but nothing to affect accuracy in any noticeable way.

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we covered this

If there is some merit in the fact that recoil does push the barrel up some, even in a heavy bull-barreled rifle, causing the bullet to aim upward before exiting the barrel: This could be proven with a simple experiment.
#1 Aim the gun at the bulls and use a simple rest to rest the gun stationary and put a device on the trigger to squeeze the trigger with nothing holding the rifle down.
#2 Do the same but put a 20lb weight on top of the rifle.

If no effect of recoil, then both #1 and #2 would have same point of impact.
But, I would bet #1 may hit higher, maybe not by much though.
I think we are distinguishing too much between the recoil and barrel harmonics. If you reduce the recoil with a weight on the gun, as in a strong hold on the rifle to your face and shoulder, you probably get less whip of the barrel. That is why you train to do the same hold each time you shoot at the bench. Some bench rest shooter have a heavy hold, while some let their rest do the holding. Its the repeatability that matters.

BigAlShooter said:

If there is some merit in the fact that recoil does push the barrel up some, even in a heavy bull-barreled rifle, causing the bullet to aim upward before exiting the barrel: This could be proven with a simple experiment.
#1 Aim the gun at the bulls and use a simple rest to rest the gun stationary and put a device on the trigger to squeeze the trigger with nothing holding the rifle down.
#2 Do the same but put a 20lb weight on top of the rifle.

If no effect of recoil, then both #1 and #2 would have same point of impact.
But, I would bet #1 may hit higher, maybe not by much though.
I think we are distinguishing too much between the recoil and barrel harmonics. If you reduce the recoil with a weight on the gun, as in a strong hold on the rifle to your face and shoulder, you probably get less whip of the barrel. That is why you train to do the same hold each time you shoot at the bench. Some bench rest shooter have a heavy hold, while some let their rest do the holding. Its the repeatability that matters.

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The gun will rotate around its center of gravity so the perfect demonstration would be to attach a 10 lb weight below the receiver, which will make the barrel try to flip up over the weight. Then move the weight from below to above the receiver. With the weight above the receiver the center of gravity will be above the bore axis so in that situation the barrel will try to flip under the receiver and move the point of impact down. We really don’t need to test this however because the physics are well understood and you could just model it in software.

Similarly as we discussed on the semi auto pistol, you see no visual muzzle rise because the slide and barrel are decoupled from the frame except for the spring so the slide moves backwards independently of the frame until the barrel hits the cam surface and transfers it’s momentum into the frame, and then the slide stops and transfers it’s momentum into the frame. At those points the frame rotates around its center of gravity and starts to flip up in the shooters hand. If we look at the slide and barrel independent of the frame, the center of gravity on the slide is going to be above the bore axis on most pistols so the recoil force on the slide will actually thrust downward on the rails of the font of the frame slightly while there is still pressure in the barrel.

Actually a great visual for all of this would be to set a gun on its side laying on the ground and actuate the trigger hydraulically. If the center of gravity is below the bore axis the barrel will flip up. If it’s above the bore axis it will flip down. If it’s perfectly inline with the bore it will just slide backwards.

But I agree, there was a really no point in being concerned about this because it’s imperceptible and it’s repeatable. Just look how much a magnum revolver flips and they are still perfectly accurate because the sights are compensated for it and the same thing happens every shot unless you change bullet weight or charge, ect….

Fun fact if you put a straight edge on the sights of a magnum revolver that is zero’d for magnum loads, the sights point up relative to the bore. Because science!