Does recoil amount and velocity affect muzzle velocity?

RockyMtnMT

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So I think this would be where a Magspeed may not give accurate muzzle vel if used in free recoil since it will not take into account the reduced speed from the rearward movement of the rifle. It will give more accurate accounting of the quality of the load but not be able to show if there is shooter error with inconsistent recoil management. Also the vel reading from a Magspeed would have to be inflated from actual vel. So as a free recoil guy I am costing my self some vel. Good news is the bc on my bullets is better than I thought. :D:rolleyes: I would like to know how much vel is potentially lost with a light rifle hold. I think 50fps is not out of the realm. This means that I am going to have to do more prone shooting so as to see if there is a difference in POI. I free recoil both ways but I suspect that the prone shot may not allow as much rifle travel as seated at the bench. In the end it all comes down to consistency and making your data match your drops. Since we started using the Magspeed we quite using mv as a variable to match drops. I think now that may not be correct. I may need to adjust mv to get drops to match data. Ugg!

Steve
 

elkaholic

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So I think this would be where a Magspeed may not give accurate muzzle vel if used in free recoil since it will not take into account the reduced speed from the rearward movement of the rifle. It will give more accurate accounting of the quality of the load but not be able to show if there is shooter error with inconsistent recoil management. Also the vel reading from a Magspeed would have to be inflated from actual vel. So as a free recoil guy I am costing my self some vel. Good news is the bc on my bullets is better than I thought. :D:rolleyes: I would like to know how much vel is potentially lost with a light rifle hold. I think 50fps is not out of the realm. This means that I am going to have to do more prone shooting so as to see if there is a difference in POI. I free recoil both ways but I suspect that the prone shot may not allow as much rifle travel as seated at the bench. In the end it all comes down to consistency and making your data match your drops. Since we started using the Magspeed we quite using mv as a variable to match drops. I think now that may not be correct. I may need to adjust mv to get drops to match data. Ugg!

Steve

Thats is a good theory concerning the magneto speed. I agree with the prone position but the downside is; OUCH! I may have to brake my 7 lb. rifle:D
 

RockyMtnMT

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Yep. I always hunt prone, but I don't like to get on the ground during a range session. Too hard to get back up. :rolleyes:

Steve
 

elkaholic

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Yep. I always hunt prone, but I don't like to get on the ground during a range session. Too hard to get back up. :rolleyes:

Steve

I have learned to shoot prone in practice because I found there can be a BIG difference at 1000 yards if you practice from a bench, lead sled, etc........Rich
 

RockyMtnMT

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I have learned to shoot prone in practice because I found there can be a BIG difference at 1000 yards if you practice from a bench, lead sled, etc........Rich

I do go out and shoot rocks in hunting situations and have not really seen a difference from the bench. Both ways though I try to influence the riffle as little as possible and I am a bag/backpack shooter. I find that I can not get consistency with a bipod. I will use shooting sticks with good success and that may be due to the fact that they still let the rifle free recoil no matter the position. Not sure if this is because of recoil varying muzzle vel but my problems with a bipod are always vertical. So now I am thinking it may have something to do with vel variations from different shooting positions that I don't experience without a bipod.

Interesting....

Steve
 

hemiford

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It absolutely will make a difference.

But, the difference is highly likely to vary from small to
immeasurably small.

The physics is indeed very simple as has been covered.

Bullet has mass & velocity. (M)(V squared) is it's kinetic energy, but MV
is it's momentum, and momentum is a vector quantity, not energy.
The "equal and opposite reaction" is due to momentum.
It is inescapable.
 

toddc

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Luckily I hunt from a bench. Bipods and me are not compatible except for a Sinclair F-class. I am lucky enough to carry my bench to my shooting spot and rock on.
 

Timber338

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All of my guns are relatively light weight, shooting heavy bullets. They all will register lower ES with my manetsopeed when I am solid behind the gun. Get lazy and Don't firm the stock to my shoulder and ES goes up. Same goes for shooting long range at targets. When I am prone and really get a solid hold my vertical dispersion is small. Get lazy and vertical error gets worse.
 

FearNoWind

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Now let's get practical here. In the amount of time it takes for the forces affecting MV to initialize and stabilize before the bullet leaves the muzzle, how much affect (if any) will it have on the final result printing on target? None of us can load accurately enough to duplicate MV from one round to another with any assured degree of accuracy. I can tell you approximately what I expect, within a certain range of numbers, from a certain load but I'm not going to bet the farm on that the second round I discharge will generate certain results in FPS different than the last one I fired. Even rocket motor firing sequences for space craft have to consider variables.
 

toddc

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Now let's get practical here. In the amount of time it takes for the forces affecting MV to initialize and stabilize before the bullet leaves the muzzle, how much affect (if any) will it have on the final result printing on target? None of us can load accurately enough to duplicate MV from one round to another with any assured degree of accuracy. I can tell you approximately what I expect, within a certain range of numbers, from a certain load but I'm not going to bet the farm on that the second round I discharge will generate certain results in FPS different than the last one I fired. Even rocket motor firing sequences for space craft have to consider variables.
With a lightweight rifle and a large case it CAN BE well over 10fps, as high as 50fps. That on top of day to day ES will really cause some issues at LR.
 

toddc

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All of my guns are relatively light weight, shooting heavy bullets. They all will register lower ES with my manetsopeed when I am solid behind the gun. Get lazy and Don't firm the stock to my shoulder and ES goes up. Same goes for shooting long range at targets. When I am prone and really get a solid hold my vertical dispersion is small. Get lazy and vertical error gets worse.
I have heard a lot of guys say that. My rigs were all OBESE so I guess I didn't notice.
 

catamountsierra

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I am still playing around with the physics and trying to figure out in detail, but I am starting to lean towards the idea that a looser hold means that there is more variance in when, relative to when the bullet leaves the barrel, that the rifle impacts the shooter and meets that resistance, basically meaning that the shooter exerts a force on the rifle and via the rifle and the expanding gasses the bullet as well... Still playing with things trying to get this figured out.
 

toddc

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I am still playing around with the physics and trying to figure out in detail, but I am starting to lean towards the idea that a looser hold means that there is more variance in when, relative to when the bullet leaves the barrel, that the rifle impacts the shooter and meets that resistance, basically meaning that the shooter exerts a force on the rifle and via the rifle and the expanding gasses the bullet as well... Still playing with things trying to get this figured out.

I used a recoil calculator and backfed the #s basically. To balance the equation on a 10lb rifle firing a 200gr at 3k if you added 10 lbs to gun weight it essentially tallied about 25 fps. I can guarantee you I am feeding more than 10lbs of mass into a 14lb Lapua. I looked for a calculator to feed it the other way and there were 10K available and I got lost quick.
Law of conservation of momentum says that MV=mv so essentially if we solve for a zero momentum solution we can figure the velocity difference on the other side.
I do know that my 40lb rigs were easier to shoot LR. They don't move much lol.
 

Clark

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I have read comments made by Bart B that said using the same rifle and ammo but changing shooters could cause a 50 fps change in velocity. I think he should know. Now that I've thought about it, I think he said 100 fps.

If a bullet weighed 150 gr and went 3000 fps and the rifle weighed 10 pounds, then the rifle will free recoil at
V1 = [M2/M1]V2 = [[150/7000]/10]3000 fps = 6.4 fps

If one shooter's shoulder is made out of marshmellows, his shot will be 6.4 fps slower than a shooter whose shoulder is made out of brass.
 
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