Does recoil amount and velocity affect muzzle velocity?

HARPERC

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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.

Just verifying I have seen his posts on this. Actually been wondering about his lack of posts recently.

I missed too many physics classes as well, and the ones I had were a long time ago.
 

alcesgigas

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Normally I'm smart enough to just read, follow, and maybe learn something from threads like this. However, changing any thing in a series of events will change the events...

I wish my Dad were alive. I'd tell him after I posted this for I know what he'd say otherwise. See he was a gunnery officer during WWII and served on light and heavy cruisers as well as a battleship. I'm thinking that 16" naval cannons--especially in triples--had to fire at differing speeds depending on a bagful of factors. One is what condition of movement (s) the ship was in when these 2000-2300# projectiles were fired at targets up to 22 miles away. I mean a beam shot was different than a stern shot was different than a bow shot (and a 24 knots different than 10 knots). And unlike we the fortunate their targets shot back...

Another variable: we attempt to account for capricious winds and other lesser influences not to mention the exquisite and laborious loading of our cartridges, etc. Maybe we should spend some time studying the other end of the forces we release. Surely there must be some effect. I feel safer with some effect than with none. Like most of the time instead of always or never.

Where is Bryan Litz, Doc Beech at a time like this? Maybe I should have stayed out of the fray and followed their example after all...
 

toddc

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It's absolutely how it works, we've seen at benches with guns that you can run free recoil but then put a hard hold on them and your velocity changes. Shooting with a muzzle brake on and of will be the same because that only effects recoil that happens after the bullet levels, it's how hard you hold the rifle during recoil with the bullet in the barrel that will show up.

Perhaps a search would yeild some info since we go through this every couple years.

I googled the heck out of it and also searched here and couldn't find it. I remember reading on it and physics says it does affect it but I cant find it. There was a pretty good article on it and I just cant find it. The reason I posted this is it came up in another thread and I opined that the hold would affect velocity and was soundly said to be crazy.
I almost thought it was in PRECISION SHOOTING AT 1000 YDS but I gave it to a friend and couldn't look it up.
 

toddc

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My understanding is that the momentum of the system remains constant, not the velocities. This means that the magnitude change in momentum (mass*velocity) of the bullet is equal to the magnitude of the change in momentum of the rifle (and likely the shooter as well); directions should be opposite or you will have the recoil pull the rifle off target by some amount.
I need to think about this. You have posed a puzzle and I am intrigued. Now I know what I can work on while I wait for my computer at work. If my poor concussed brain wasn't so tired, I might try tackling this tonight, but I think it will have to wait for tomorrow. I haven't tackled a question like this in a while and I think I am looking forward to it; does that make me crazy?

Yes the equation is MV=mv per the law of conservation of momentum but from what I could find the difference is the recoil VELOCITY. If someone a lil physics smarter can calc it I would be interested to see the equation used. I usually shoot 40lb 338s and my 14 lb 338 I am seeing higher ES and worked on my hold and they dropped. However I am also breaking in the barrel so there are variables involved.
 

elkaholic

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I am certainly no expert on this, but it would make sense to me that it would have SOME effect. Would the principle of jet engine propulsion apply at all here? .......Rich
 

gohring3006

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Now you guys got me thinking the ES is not all about my loads...
Thick jacket,
No jacket,
Prone
Bench!!!
I'm never going to get any sleep!!!
 

toddc

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Now you guys got me thinking the ES is not all about my loads...
Thick jacket,
No jacket,
Prone
Bench!!!
I'm never going to get any sleep!!!
Part of the reason I brought this up is I was seeing higher ES than I wanted on my M112 338. All of my previous 338s were 100% bench guns and most weighed in the 40lb range. My 1st outing with the new Savage my ES was higher than I was used to, of course this is during barrel break in and load development so I let it go.
Then a thread came up about terrible ES and I remembered that HOLD can influence MV. My next session with the Lapua I really concentrated with HOLD and my ES shrunk. My first time out I was to some extent learning to ride a 14lb Lapua, my 40lb Edges didn't need this.
Just one more variable in LR shooting.
My more consistent HOLD didn't seem to shrink 100yd groups, BUT it did cut my ES by 50%, of course some of this could be related to barrel break in or chrono placement but research into potential deviation shows that a HIGH RECOIL VELOCITY will leave more room for this effect. If my Lapua was 40lbs as well I am sure it would have a much smaller deviation
 

Barrelnut

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I'm more with FearNoWind on this and here's why.

I think Einstein's theory of relativity is more important than the equation for acceleration and momentum.

The "relative" part has to do with the fact that the rifle, bullet, and explosive pressure created by the powder are relative to each other, and ALL are set in a rearward motion at the same time as the rifle is recoiling. In this scenario, all three are constants and the same, so the bullets comes out of the muzzle at the same speed each time no matter how fast the whole object (the rifle, bullet, and pressure) are accelerating backward.

Now, this changes a bit once the bullet is free from the barrel. The bullet has the same velocity, but it has a slightly longer distance of travel to the crony. This is assuming a stationary crony set say 15 ft. from the muzzle. Now if you attach the crony to the rifle (Magnetospeed), it is now also moving relative to the rifle and would not register any difference in speed.

Just another way of looking at it.
 

Barrelnut

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Plus --- since the bullet is moving in reverse with the barrel. If it was moving away from the static placed chrony at say 10 FPS, I think it would indeed appear to the static chrony that it was going 10 FPS slower. It would not appear this way to the Magnetospeed as it is moving relative to the bullet. So... I guess you could use a acceleration formula to calculate the effect of not holding the rifle with the same shoulder pressure. So... never mind.
 

THEIS

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Hello,

Short answer to your question....I would have to say yes. I am digging up the formula(s) that can be used to "prove" that.

I can say that when we submitted test rifles to DoD for the "PSR" program we had to supply ammunition that had to fall between x MV and y MV with a set acceptable MV deviation. All ammunition testing was fired in the rifles submitted...but here is the kicker to that. Each manufacturer had to supply our own firing fixtures for the rifle to test the MV deviation, so I would say that was to eliminate any MV deviation based off shooter "interference". We supplied with a floating firing fixture that let the rifle recoil, that incrementally slowed down due to spring loaded ball bearing rollers. Other manufacturers supplied lead sled type fixtures. We tested our supplied ammunition from our rifles placed in their fixtures and vice versa....MVs were different even though was exact same ammunition and fired in exact same firearm. Only component in equation changed was the firing fixtures.

Side question :).....do you think the air volume in barrel that gets compressed and forced out of barrel extremely fast affects second recoil impulse and do muzzle brakes cause an interference within that recoil impulse? And is there a shooting principle that can help negate that interference?

THEIS
 

elkaholic

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Hello,

Short answer to your question....I would have to say yes. I am digging up the formula(s) that can be used to "prove" that.

I can say that when we submitted test rifles to DoD for the "PSR" program we had to supply ammunition that had to fall between x MV and y MV with a set acceptable MV deviation. All ammunition testing was fired in the rifles submitted...but here is the kicker to that. Each manufacturer had to supply our own firing fixtures for the rifle to test the MV deviation, so I would say that was to eliminate any MV deviation based off shooter "interference". We supplied with a floating firing fixture that let the rifle recoil, that incrementally slowed down due to spring loaded ball bearing rollers. Other manufacturers supplied lead sled type fixtures. We tested our supplied ammunition from our rifles placed in their fixtures and vice versa....MVs were different even though was exact same ammunition and fired in exact same firearm. Only component in equation changed was the firing fixtures.

Side question :).....do you think the air volume in barrel that gets compressed and forced out of barrel extremely fast affects second recoil impulse and do muzzle brakes cause an interference within that recoil impulse? And is there a shooting principle that can help negate that interference?

THEIS

Good answer followed by another good topic:)
 

toddc

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Good answer followed by another good topic:)

Now I really have a headache.

I knew that velocity had to be affected by recoil impulse issues.

Air running out of a barrel and the interaction with the brake.....wayyyyyy beyond my action/reaction level physics abilities.

I would guess that said air in barrel would act on the brake, but air subject to thousands of PSI does weird things especially when combined with everything else happening in a firing event.

WAAAAAYYYYYYYYY past my physics remembrance lol.:)
 

elkaholic

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Now I really have a headache.

I knew that velocity had to be affected by recoil impulse issues.

Air running out of a barrel and the interaction with the brake.....wayyyyyy beyond my action/reaction level physics abilities.

I would guess that said air in barrel would act on the brake, but air subject to thousands of PSI does weird things especially when combined with everything else happening in a firing event.

WAAAAAYYYYYYYYY past my physics remembrance lol.:)

I thought physics was something you got from drinking water in Mexico:D
 

toddc

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I thought physics was something you got from drinking water in Mexico:D
Haha I lived in Mexico running a guide business for 6 yrs. If anyone has it I DO!
I do actually have some left over gut issues from my time down there. Unless I count increased reading time while destroying a toilet, I don't think it helped my physics knowledge much, other than proof positive what principles a rocket engine has....which is what your guts turn into after a bug down there.
 

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