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I'm starting a thread regarding "muzzle jump". We started talking about this in another thread so to keep from hi-jacking the other thread I thought I start on this subject in a new thread.


We all know a pistol (or even a rifle for that matter) will jump due to recoil. Good old Mr. Newton's Laws. The question is does this jump or any part of it, occur when the bullet is still in the barrel thus having an affect on point of impact? Remember we're speaking about pistols.

The Myth Buster 73,000 frames per second video was mentioned. Maybe someone can post the link to the video for me. The high speed video shows the bullet leaving the barrel. The bullet APPEARS to exit before the recoil impulse moves the pistol. However it is also pointed how little the muzzle needs to move to affect the point of impact 25 yards down range.

I've always operated under the assumption (and that may be my error) that the higher velocity (thus the bullet exits the barrel sooner) or a shorter barrel will have different points of impact as velocities vary. I do not have any hard data to support this assumption just urban legend and old shooters tales.

So fellow members, what are your thoughts?

Grumpy
 

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I would think The only way to tell would be to place the gun on a surface, not connected to anything, and have the hammer drop and compare it to the same gun mechanically locked in place. And you would need enough shots to rule out ammo difference.
 

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Howdy Old Grumpy, I do know that long gun's barrels do whip (anyway Elmer Fudd's did when he was shooting at Buggs Bunny) I saw a government video about it along time ago. Don't really know about a handgun, but if I did not have to put money on it I would say that they do. Barrel harmonics I think they call it.
 

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First, thanks Old Grumpy for starting this thread.

I think we all can agree that (speaking of 1911 pistols) the slide moves rearward about 0.10" before the bullet exits the barrel. But, the question is, at least as I see it, does the linear movement of the slide translate into rotational movement which would affect the POI?

It must be so, because my experience has been that a slower bullet will impact higher on the target than a faster bullet and barrel/slide rotation appears to be the only explanation.

But, in the high speed photography, I just don't see any rotation. But as Trigger Creep pointed out in the other thread, it doesn't take much. Most likely, rotation does occur, but it's imperceptible, even in high speed photography.
 

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I see the slide move before the bullet exits.

Here is the 1,000,000 frames per second video: https://www.youtube.com/watch?v=otpFNL3yem4
Inconclusive-the slide moves slightly presuming that something didn't change in the camera mount, but I can't detect that the barrel tilts or even starts to unlock from the slide in that video.

Perhaps a Ransom Rest could be used to determine something about point of impact WRT bullet weight and velocity (that would be interesting if it hasn't been done already-lacking either device I'm not volunteering to conduct the research!) but I believe that in the final analysis human factors will have a greater influence on POI than any slight movement of the slide and barrel.
 

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I can state I believe it to be true. When I loaded 240 grn 44 mag out of my SBH for mid range loads, it shot way high. Hotter loads came down.

After googling, apparently this is a common issue with heavy slower bullets than what the gun's intended loads are. Contacted Ruger for taller front sight and POI matched POA when running slower rounds.

The barrel was rising just enough as the bullet going down the tube to throw the rounds high.
 

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Discussion Starter #9
There is a lot of geometry involved in the whole force opposite force thing. Viewing these two slow motion videos you do see the slide starting back before the bullet exits. Has that same force (the recoil) been transferred to the shooters hand (if they were hand held). The grip angle (on a 1911) could possibly cause the muzzle to rise. However this, at least the majority of it, occurs once the bullet has exited the barrel. At least that is the way it appears to me.

So in these extreme close-up shots what appears to be thousandths of an inch movement could develop into an inch or two at 25 yards.


Grumpy
 

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Pardon me, fellows.

It's not slide movement. That is a 'red herring'. Slide movement is straight back relative to the frame, and usually delayed by locked-breech mechanisms. That's not what we're looking at.


The important thing to consider is the gun's rotation in the hand. The whole gun and the hand. Frame, slide, barrel, hand and everything rotating upward together. Only 0.005" muzzle rise makes a 1" difference on target.




I know you are all new to this, but upward rotation in the hand is part of handgun technology known since the 1700's with flintlock pistols.

We all know RIFLE sights make the barrel point upward, because the trajectory of a bullet needs to travel upward so gravity can pull it back down to target level 100 yards (or more) away.

But a handgun isn't a rifle because typical traditional handguns are held in the hand(s) which rotate on the wrist. [The Chiappa Rhino is the exception here, that's why I say 'Traditional' handgun, the Rhino barrel is mounted low so it rotates differently.] Traditional handguns and the whole hand begin upward rotation as soon as the bullet begins to move. This has been known for centuries. It may be new to you, but it has been known since Grandpa was born.

Very slight upward movement at the muzzle translates to inches of movement on the target. With a 5" barrel, 0.005" rise of muzzle raises point of impact 1" at a target 25 yards away. Do the math, if you're good at trigonometry.


I know many of you will argue against that, based on nothing more than what you THOUGHT happens during handgun discharge. I urge you to reconsider.
 

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Muzzle jump with a handgun.....

Trigger Creep is correct! When a the back of a fired cartridge slams against the breech face, the gun will try to rotate and the barrel will lift upward since the gun hand is lower than the bore axis. This is one reason why using a high grip helps to reduce the effects of recoil and muzzle lift..... I always had a problem using the "plow handle" lower grip of a Ruger .44 Blackhawk.... With stout magnum loads, the gun always shifted in my grip under recoil!

Muzzle jump is a known phenomenon when shooting handguns. In a standard .45 acp 1911, a 185 gr. bullet with a 900 fps velocity will shoot lower on target than a 230 gr. bullet at 900 fps....due to the effect of muzzle jump. The heavier bullet imparts more recoil force, so the barrel moves upward before the bullet leaves the bore....Even though the upward movement is extremely minute, it affects the angle of the bore to the POI, so the gun shoots higher.
 

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When a the back of a fired cartridge slams against the breech face, the gun will try to rotate and the barrel will lift upward since the gun hand is lower than the bore axis. 4
This is persuasive to me. There never was any question that the handgun (except Chiappa Rhino) rotates in the hand, and therefore the sights are not parallel to the centerline of the bore. But, the question that the high speed photography raised in my mind, was does this rotation occur while the bullet is still in the barrel?

Another poster mentioned that the link-down (in a 1911) begins when the slide has moved 1/10", so possibly the link-down process changes the angle of the barrel while the bullet is still in the barrel?

I don't think anyone questions the phenomena, I'm just trying to understand it.

I believe a Ransom Rest allows the pistol to rotate when fired. What would happen if the pistol was clamped rigidly enough to allow no rotation. Would this slower bullet higher and faster bullet lower on target still apply?
 

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While looking for the sweet recipe for my 9mm RO I found the same results as the former comments about velocity and POI. The heavier, slower bullets had a significantly higher POI at 25 yds. and a lower POI at 50 yds. I am assuming the higher POI at the shorter range was due to muzzle lift while the bullet was still in the barrel and the lower POI at longer range was the bullet losing velocity at a faster rate than the lighter faster loads. Interesting stuff.
 

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Oh, you're right about the Ransom rotating-I'd forgotten about that. It's emulating the wrist of a shooter!

Now if the slide is moving back that means some force is trying to keep the frame at rest so as the bullet is being accelerated, equal and opposite forces are applied to the breach face. In the case of a 1911 these forces are transferred to the frame through the recoil spring and the main spring (and whatever drag there is between the frame and slide and the forces required to unlock the barrel) initially, thence to the shooter's hands and wrists.

I still think the human factors are the greatest influence on POI. How else could the not infrequently seen factor of "anticipating" or "pushing" cause low impacts?
 

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The different impact points caused by velocity changes have nothing to do with muzzle movement!!:eek:
 

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The different impact points caused by velocity changes have nothing to do with muzzle movement!!:eek:


Are you saying that the impact points change because of gravity instead of muzzle rise?
 

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Walter's comment, at least in my way of thinking, says velocity affects the drop or rise of the point of impact more than muzzle jump.

All bullets travel in an arc. As pointed out the sights are designed so the axis of the bore has a very slight rise. The bullet exits the barrel on a very slight upward path and as it travels down range it will rise and then fall according to where on the arc it is. The heavier the bullet or the lower the velocity the more pronounced the arc. So depending on the range and the arc the point of impact could be above the point of aim or below it.


In rifles the "flatter" shooting calibers are usually the higher velocity calibers and often the lighter projectiles in those calibers because the arc is shallower over the distance being shot.

I think I had some trig in High School, the class after girls 101 and before horseplay 301. :)

Grumpy
 
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