Fieldcraft Recoil off bipod

[mgd45]

Re: Recoil off bipod

I'm still new to this long distance shooting stuff......so sometimes I get frustrated after a range day when I think my group size isn't good enough.

For instance, Last weekend I did some shooting at 600 yards with a buddy to help him get some dope for his scope. My first 5 shots were at 0745 in the morning without any dry firing warm ups, just simply dropped to the ground and popped off 5 rounds at the target. The target was a 6 inch circular red dot on a regular sheet of computer paper.

At first I was upset, because although all my shots landed with in the red cirlce....I didn't think the group was tight enough. That is until my buddy placed the paper over my chest, and said, "What the hell is wrong with that??" "Ya got 6 shots at 600 yards in the center mass of a person's chest....."

Sometimes I gotta put things into perspective, itty bitty groups are impressive, but sometimes ya only get one shot. Thanks for the help LL. I'll be putting your advice to practice on the range this weekend.

 

[ckirkc]

Re: Recoil off bipod

i totally hear you montana, bullets are torquing our barrels causing the dreaded bipod hop. Which is why i have created AT200 lubricant (anti torque lube). Just check out this high speed footage of an m1a rifle being fired after the application of at200. straight back recoil all day long. I have gobs of it for sale at 179 dollars a gallon or trade for large rifle primers.
ANTI TORQUE

Anti Torque 2

 

[skibum]

Re: Recoil off bipod

I agree Frank. I think it was my bad mental mojo left on SH22 that screwed up Graham. Just comes down to more trigger time on my part. When is the next PR1-2 at RO. I think the third time will be the charm for me! Check your pm, send a question on video cameras.

Jim

 

[beezaur]

Re: Recoil off bipod

Is there a way to upload a pdf? I made a drawing of what I observed in my testing a few years ago.

Scott

 

[Lowlight]

Re: Recoil off bipod

video tape yourself, the PDF doesn't say anything... but what you wanted it too.

I have to agree with sbrbiker the little tiny bit of torque that might be introduced is not going to out weigh the recoil coming straight back from the bullet leaving the muzzle. In a 20" rifle with a 1-10 twist how many "turns" does the bullet make inside the barrel ?

What 99% of the people see are the effects produced by the shooter where improper body position creates an angle at the shoulder causing the rifle to move off target.

Where are the "Left-Handed" shooters, I bet their rifle jumps to the right ?

 

[Lowlight]

Re: Recoil off bipod

this Kids gun, shooting off a bipod from the left hops to the Right!
<object width="425" height="350"> <param name="movie" value="http://www.youtube.com/v/1fOzbxOEOl0"></param> <param name="wmode" value="transparent"></param> <embed src="http://www.youtube.com/v/1fOzbxOEOl0" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"> </embed></object>

 

[beezaur]

Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">video tape yourself, the PDF doesn't say anything... but what you wanted it too.

I have to agree with sbrbiker the little tiny bit of torque that might be introduced is not going to out weigh the recoil coming straight back from the bullet leaving the muzzle. In a 20" rifle with a 1-10 twist how "turns" does the bullet make inside the barrel ?

What 99% of the people see are the effects produced by the shooter where improper body position creates an angle at the shoulder causing the rifle to move off target.

Where are the "Left-Handed" shooters, I bet their rifle jumps to the right ?

</div></div>

Frank,

I have complete confidence in your abilities as a shooter and instructor. If you say proper form can prevent bipod hop, then I am sure that is true.

But that notwithstanding, send anyone else out with a rifle and high-speed accelerometers, and they will get exactly the sae result that I have gotten. Namely, that bipod hop can happen as a result of a rotating rifle on a bipod with a pivot.

It won't always happen that way, I'm just saying that it can. I'm not going to pretend to have your shooting expertise.

Regular videos don't show you anything. For one thing, the effects happen on millisecond timescales, which are impossible even to see at normal speed. For another, you have to have high resolution and special software to measure the movement. I am not going to spring for high-speed, high-resolution video, but it would be an excellent project for someone more involved in training to do.

Some of my accelerometers are pretty basic, not really even professional grade, but they are pretty sensitive and do measure on the timescales I need. For example, on my rifle that weighed maybe 15 lbs and shot from a solid prone position, I can plainly see the rifle's movement from when the trigger breaks and the firing pin accelerates toward the primer. I can resolve the pin hitting the end of its travel and the motion of the rifle as the bullet is pushed down the bore. I can measure when the bullet leaves the rifle, and the vibrations afterward.

You'd have a pretty hard time getting all that from video.

So no, the pdf is not just saying what I want it to. My opinion is based on my experiments and data. I've long ago given up the idea of forcing my preconceived notions into my work. There are just too many things that are counterintuitive. I try to go only where the data leads.

Scott

 

[Lowlight]

Re: Recoil off bipod

so how does that millisecond of right hand torque make this kids' bipod and rifle go to the right ?

Or better, how does something so small that requires you to measure it do to that degree create the jump as far as many people experience, especially when you consider the force of the recoil going straight back ?

 

[ckirkc]

Re: Recoil off bipod

Watch the high speed footage I have posted. Watch them both a couple times they clearly show straight back recoil absent of torque

 

[ckirkc]

Re: Recoil off bipod

The first vid is a little squirrly until it fully loads, you have to play it a couple times. In both vids the shooter has rested his scout m1a on a saw horse.

 

[beezaur]

Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">so how does that millisecond of right hand torque make this kids' bipod and rifle go to the right ?</div></div>

I only measured motion at a couple of places on the rifle, so I can't resolve effects from the support of the shooter. All I see is movement at the instrument.

You could have a situation like this:
1) bullet is accelerated, rotating the rifle counterclockwise (looking downrange)
2) rotation is against the shooter's body, which is fundamentally elastic
3) after the bullet leaves the barrel the shooter's body, eformed by recoil, rotates the rifle clockwise
4) you get bipod hop to the right

But that is all hypothetical. I don't have data that supports or rejects it.

In the end, we know the support from the shooter's body is important. Otherwise you would always get bipod hop (or not), with the shooter's form irrelevant. Obviously that is not the case.

My interest is, when it does happen, what causes it.

My data show a very brief rotation when the bullet is in the barrel, then an "unrotation" that starts as soon as the bullet leaves. When the rilfe is on a pivoting bipod, there is lateral movement according to the direction of rotation. Which direction that movement is in (right or left) depends entirely on what is dominant: rotation or "unrotation."

This rotating and unrotating takes place in a few milliseconds. After that all you have left is lateral velocity. In the video of the kid we cannot see any rotations that might have happened - it could easily happen in between frames. All we can make out is the end result: the lateral velocity.

I suspect what happens with the kid is that the "unrotation" is dominant, so he gets a right hop while I (a right-handed shooter) get a left hop.

The implications are that
1) significant rotation can be caused by the shooter's body
2) for right-handers, body effects and bullet effects add;
for left-handers, body effect and bullet effects act oppositely
3) body effects can dominate over bullet effects

Just hypothetical.

Scott

 

[Lowlight]

Re: Recoil off bipod

Dude,

You are way over thinking this... its clearly caused by the input the shooter exerts on the rifle. Its cause and effect, "If you do that... this is what happens.

Hypothetical... of course it is, because you can't come to terms with the fact, you, as the shooter have a far greater input to the system which is my point and always has been from my first post. Stop blaming the rifle and take responsibility for yourself.

This idea of creating scientific excuses for poor shooting is taking hold of the internet thanks to guys like you, who measure and model and yet, don't go out and actually shoot and observe.

Get off it, put the degree away for an hour and shoot.

Even with video evidence you are still looking for the easy way out...

 

[beezaur]

Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">how does something so small that requires you to measure it do to that degree create the jump as far as many people experience, especially when you consider the force of the recoil going straight back ? </div></div>

The rotational impulse is extremely brief. But when you have the rifle resting on a bipod that pivots, the rifle necessarily has to move laterally or the bipod has to move on the ground. Something must move.

By the time the bullet exits the bore (or shortly thereafter) the rifle has been set into motion sideways.

The rotating force imparted by the bullet isn't really that small. It is fairly significant. But it happens so fast that you need special instruments to see it.

I'll have to go find that old computer where my data is, or reshoot some of it.

Scott

 

[Lowlight]

Re: Recoil off bipod

Okay, I am done... don't bother getting the data, I believe you, it is huge and the bigger the bullet the bigger the force, etc, etc...

I refuse to argue with science...

 

[beezaur]

Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Dude,

You are way over thinking this... its clearly caused by the input the shooter exerts on the rifle. Its cause and effect, "If you do that... this is what happens. . . .</div></div>

But why? What is the exact mechanism?

That is what I am after. You need to know the why if you want to understand it. Otherwise you are stuck with endless trial and error.

Scott

 

[ckirkc]

Re: Recoil off bipod

Are we watching the same video there is no kid in the vid I posted only a shooters hand. The vid is slow enough to see the flash suppresor flex I'm sure if there was rotaion you would see it.

 

[Lowlight]

Re: Recoil off bipod

It's simple, we are not consistent in the pressure we put on the rifle.

1. Bad trigger pull
2. Angles introduced at the shoulder where the rifle moves against
3. sympathetic squeezing or movement with the support hand
4. improper cheek weld with force of your face pushing the rifle to right which causes it to go left
5. not loading the bipod but in fact pulling it backwards

The list of shooter errors is long...

 

[beezaur]

Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ckirkc</div><div class="ubbcode-body">The first vid is a little squirrly until it fully loads, you have to play it a couple times. In both vids the shooter has rested his scout m1a on a saw horse. </div></div>

A rifle sitting on a sawhorse is free to rotate. I don't think you'd always see the rotation even in a video like that. It's fairly small.

When you have a pivoting bipod, it can turn rotation into lateral motion. The lateral motion is much larger and more easily seen.

I really need to redo my experiments, refined with Lowlight's suggestions. Now to get some time off.

Scott

 

[ArcticLight]

Re: Recoil off bipod

So how come this doesn't happen when I shoot a sling?

I'm with Frank on this one, analyze this to death and still come up with the fact that my rifle doesn't hop when I use a bipod - and I don't use a pivot as it's just another piece to throw off good shot placement...

Best thing to do is get someone out with you - go shoot -and have them coach and watch.

I bet in the end you are anticipating recoil and pushing the rifle....and I've done it, both in sling and on bipod....

 

[lanwickum]

Re: Recoil off bipod

In any case the equation to determine the amount of torque the moving bullet will apply to the gun is:

M = (1.7x10^-9 x W x R^2 x n )/T
M= torque in lb ft
W = bullet weight in grains
R = radius of bullet diameter in inches
n = RPM of bullet
T = time bullet is in barrel in seconds
I applied this to a 50 grain .22 caliber leaving barrel at 300000 RPM with a barrel time of 1 millisecond. I got .31 lb ft torque. Determining how much the gun will move before the bullet leaves could be figured but it depends on so many things that would be hard to pin down that I wonder if you could ever get close. For example, friction at the gun support would probably be very tough to predict.


I stole this from benchrest central. How many guys want to figure the torque with 308 175grn FGGM and say 10 twist barrel?

Hope this helps to put what is happening into perspective.

My view while shooting: It happens, but don't use it as an excuse.

Need to clear things up as is seems my statements can easily be miss read or have miss wrote them.
I completly agree with LL. It is tiny and ALMOST doesn't exist. The "almost" part was my disagreement as I read LL saying it doesn't exist. LL has clearly stated he knows and admits it does exist. Hope I made that clear. I am offten bad at doing so.

 

[Tburkes]

Re: Recoil off bipod

This happens over and over again, whether the discussion is bipod hop, spin drift, coriolis effect, lock time, mover speed calculation, etc, etc, etc.

The engineers have to chime in with their calculations, computations, observations, that yes, so and so is real and does affect the down range performance.

Time and time again these threads get thrown off into never never land just because some guy has an accelerometer attached to his rifle somewhere, or whatever the case may be, and the thread degenerates into a negative return for the people who are trying to learn.

YES, all these things exist and can be measured. The MAIN thing that keeps being forgotten by all of the "experts" on the mathematical formulas is the most important thing, the HUMAN FACTOR, the loose nut behind the trigger.

This is a shooting site dedicated to helping people hit the target at whatever range with a rifle bullet. It's not an artillery site trying to help people hit targets with 1500 pound 16" shells. If it were such a site then you'd all know that spin drift will throw your 16" 1500 pound round off 4 feet at 20 miles, but it's not such a site.

What keeps being told to people who have to throw these threads off is that while, spin drift, coriolis effect, lock time, and mathematical formulas do exist, they have so little to do with making the rifle bullet hit the target that you don't need to worry about all that shit. There is enough you do need to worry about, mainly all the human factors that YOU are introducing into the equation, that you don't need to get all wrapped around the axle by all this other mathematical crap.

For example, I've seen time and time again here, on other sites, and on the range, where someone asks "what hold do I need to hit this mover"? Guys will spout off the formula that takes, distance from target, distance mover is moving, mover speed, size of target, time of flight of the bullet, wind direction, wind speed, and calculate "X" hold will hit the target. Then the guy gets down on the ground and holds "X" and can't figure out why he's not hitting the target. I mean hey, he's got the formula down exactly, he'd double checked his numbers three times, WTF, "why can't I hit the freaking target"?

He forgot the most important input, his own personal lock time. In this instance what's lock time? The mathematical lock time doesn't count here. The "lock time" in the real world is the time it takes for a particular shooter to tell himself, "self, drop the hammer on that mover now" until the bullet exits the muzzle. One more time, Lock time is the time it takes from when this guy consciously make the decision to press the trigger until it takes the bullet to exit the muzzle. It's not the formula that everyone thinks about, that being the time it takes the firing pin to ignite the primer when it is released. That's the mathematical formula that doesn't mean crap when you're laying on the ground trying to hit the target.

A perfect example that is used when discussing this at a rifle class down at RO is that one well known shooter has to lead the mover almost two mils to hit the mover, and he can hit the mover very well. Another well known shooter has a lead on the same exact mover of only a little over 1 mil lead, and can knock the shit out of that mover time and time again. Which one is correct? Well...they both are, cause they both hit the mover.

They don't worry about all the mathematical crap, they believe the bullet.

So, does torque happen, and have an effect on the bipod, YES. Does it happen enough that it needs to be taken into account for a guy lying prone on the line at a match, or looking through a window from the back of a room at an IED carrying insurgent?

HELL NO IT DOESN"T

Proper application of the Fundamentals Of Marksmanship is what is going to help both guys hit their targets when the chips are down.

I have never heard Frank, or Jacob say that torque, spin drift, or coriolis effect, don't exist, in fact they'll be the first to tell you that they do indeed exist, BUT, they don't effect the discipline that we are all on this site for enough that it matters in the real world. The FOM are what matter over all the mathematical formulas and have a much greater influence on whether or not you're bullet will hit it's intended target.

So stop clouding up the issues by jumping up and saying stuff about mounting barrels on saw horses and attaching accelerometers can prove that so and so does really exist, cause you're not helping the guy who wants to know why his bipod jumps around at all.

 

[mgd45]

Re: Recoil off bipod

I think that post....right there about sums it all up!!

 

[beezaur]

Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tburkes</div><div class="ubbcode-body">The MAIN thing that keeps being forgotten by all of the "experts" on the mathematical formulas is the most important thing, the HUMAN FACTOR, the loose nut behind the trigger. . . .

That's the mathematical formula that doesn't mean crap when you're laying on the ground trying to hit the target. . . .</div></div>

Geez, Tony, how many times did you use the word "mathematical" with palpable disdain?

Why do you think it is that you have all this great equipment that lets you put a cold bore shot on target at long range?

Fancy scopes with optical coatings and refined mechanisms?

Fine barrels and actions with superior metalurgy?

Advanced materials in stocks and other equipment?

Laser rangefinders? Night vision? Suppressors that are small and effective? Ballistics software?

You owe all that stuff to nerd boys and their math.

No one gripes when they use all the fruits of such labor. Why bitch about the people who make it possible?

Scott

P.S. When you study something like recoil dynamics you have to isolate the thing you are studying, i.e., remove the human factor. Doesn't mean you are forgetting it. It means you are ignoring it on purpose to solve your problem.

 

[Lowlight]

Re: Recoil off bipod

Using science and math to advance equipment is different from using it to explain away problems with shooter error.

 

[beezaur]

Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Using science and math to advance equipment is different from using it to explain away problems with shooter error. </div></div>

Well, I'm not trying to explain errors away.

I do a lot of work with contractors. I design stuff, they build it.

Building things takes a great deal of skill. Would you want an engineer to build a complicated structure? Not hardly. An engineer can be handy just like anyone else, but you need someone with a lot of skill to build something well.

But by the same token, you don't want even the most skilled builder trying to do complicated design. There will be things they miss that they aren't even aware of.

You need both, and they have to listen to one another. Otherwise you get some half-baked thing that doesn't do what it is supposed to do.

Scott

 

[Lowlight]

Re: Recoil off bipod

No, I think you were saying all along the "hop" the shooter was experiencing was caused by the torque produced by the rifle... so you were in fact saying, the shooter's error in position was not a error but a scientific reality, that bipods hop because of torque. Just like your handgun torques in your left hand more than your right, or something to that twisted effect.

What you just wrote, sounded like blah, blah, blah, I'm really righ the science says so, blah, blah, blah.

 

[Tburkes]

Re: Recoil off bipod

Scott, there's no disdain at all for the mathematical "nerd boys". Some of my best friends are so much smarter than I am that I wonder if we're friends just so they can have cheap entertainment at my expense.

I don't worry about the quarry where the Aluminum ore is mined that goes into the scope tube. I don't call the scope companies to try to find out where they get their glass and what goes into the glass coatings. I don't worry about the inner mechanisms that make the scope repeatable time after time, year after year.

All of that isn't going mean one thing to me when it comes time to hit a target far away. All I want to know is that the glass I'm using is the best that I can afford.

I don't call Bartlein barrels to enquire about the CNC machines they use to make their barrels. I don't worry about the metallurgy that goes into the structure of the steel. I don't care about the heat treatment or the order in which they heat treat and cut the riflings on the barrels either.

I don't call McMillan, or Tom Manners to ask about stock construction, or the order and direction that they lay the fiber glass matt, or care about the type of resin they use to make it all come together.

Who's griping, who's bitching about all of that? I most certainly am not. I hold these guys, maybe you are one of them, in the highest regard. They, you, make possible things I can't comprehend how it is they were conceived in the first place. I worked with engineers in the chemical industry for 18 years who were head and shoulders smarter than I was. The good ones also listened to the guys who ran the process day in and day out and could communicate on the laymans level that which made the process easier to run and understand. They would also listen to us operators, and understand and acknowledge as true, when we would tell them we didn't give a damn about the theory behind this process, just tell us how to make it run better. We had high regard for these guys and what they could figure out because they were just so much smarter than we were. They didn't try to baffle you with bullshit and try to impress you with their degree.

Your quote: "P.S. When you study something like recoil dynamics you have to isolate the thing you are studying, i.e., remove the human factor. Doesn't mean you are forgetting it. It means you are ignoring it on purpose to solve your problem."

You didn't hear a thing I said did you?

We're not studying recoil dynamics on the molecular scale, we're trying to figure out why they guy's bipod jumps when he's laying in the dirt or deck. With your statement you've erased they guy, the biggest factor, that is causing his problem, the human factor.

You'll never get it figured out in the real world in this instance because you've erased the biggest factor on your chalk board and are only left with the saw horse and accelerometer.

I'll wager this, and I'd put a lot of money on this. You take two guys who have no experience shooting rifles what so ever and you have one start reading the Hide online training and then go down to RO for some hands on training. The other guy will go study with you about recoil dynamics and you have him hooking up barrels on saw horses with accelerometers attached. Let's give both guys six months of study and then we'll enter both of them in a rifle match somewhere and see who has the better performance. Will it be the guy who has studied for six months in the proper fundamentals of marksmanship, or will it be the guy who can put us all to sleep with the formulas and theory behind why his bipod jumps when he pulls the trigger.

All of my money is on the guy who was in the field.

You sound like a nice guy and all, but you're still clouding, no blocking, the issue with things that don't matter on the range, because you're still refusing to acknowledge how much the human factor over rides your accelerometer in this discipline.

 

[beezaur]

Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">No, I think you were saying all along the "hop" the shooter was experiencing was caused by the torque produced by the rifle... so you were in fact saying, the shooter's error in position was not a error but a scientific reality, that bipods hop because of torque. . . .</div></div>

We are missing one another.

I am saying that bipod hop is because of both torque and shooter error.

The forces that cause the pod to hop are ultimately rooted in torque. But, there are things the shooter can do (proper form) to counteract it.

From my point of view, it would be better if there was a bipod that was not prone to hopping. That ends up making the shooter's job easier. It's one less thing he has to compensate for.

For example, I suspect that bipods mounted just below the barrel (AI AW, Sako TRG, etc.) minimize torque. They should, but I don't have one to measure, so I can't say for sure.

So that is a case where abstract theory might result in a real world improvement: use a different bipod and have an easier time as a shooter.

Anything you can do to make the system insensitive to error is a plus.

Scott

 

[Lowlight]

Re: Recoil off bipod

So, here do this, go back to your drawing board and measure the amount of torque to the side, versus the amount of recoil to the rear and let me know what you come up with... because there is no problem with a bipod.

Why don't people experience movement of the rifle to the side on a bag ? Why do left handed shooters "torque" in the opposite direction, you still haven't acknowledged the other circumstances where the results are equal yet opposite of the science.

 

[beezaur]

Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tburkes</div><div class="ubbcode-body">
I'll wager this, and I'd put a lot of money on this. You take two guys who have no experience shooting rifles what so ever and you have one start reading the Hide online training and then go down to RO for some hands on training. The other guy will go study with you about recoil dynamics and you have him hooking up barrels on saw horses with accelerometers attached. Let's give both guys six months of study and then we'll enter both of them in a rifle match somewhere and see who has the better performance. Will it be the guy who has studied for six months in the proper fundamentals of marksmanship, or will it be the guy who can put us all to sleep with the formulas and theory behind why his bipod jumps when he pulls the trigger.

All of my money is on the guy who was in the field. . . .</div></div>

I agree with you. The guy who was trained to drive the weapon will be better at driving the weapon.

But, which one of those guys would you want to design a new bipod or stock?

Scott

 

[beezaur]

Re: Recoil off bipod

Here's a good project for someone with a video camera and a laser.

Stick a flat mirror on the side of the stock. Shine a laser on it from a fixed position (like a tripod) so that it reflects off the mirror and hits a piece of blank paper.

This will magnify any rotational movement of the rifle. I don't know if you could catch the driving torque from the bullet being spun up, but it would be interesting to see what comes out of it.

I think at the least it could be a training aid.

Scott

 

[Tburkes]

Re: Recoil off bipod

THAT is what we're all about here, driving the weapon. This is not the Engineering Hide, it's Sniper's Hide, it's all about shooting.

Which one would you want shooting at the bad guy that's shooting back at you?

 

[beezaur]

Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tburkes</div><div class="ubbcode-body">
Which one would you want shooting at the bad guy that's shooting back at you? </div></div>

I want the best shooter.

But I've decided to boycot engineers. So I will insist that he uses a wood-stocked M40 with a 3x9 Redfield off the ruck.

Scott

 

[marduk185]

Re: Recoil off bipod

ok fellers, hows come my rifle hops right not left either from bipod or sandbag? is it broken or have torque inversion due to strange polarity alignment on a ley line? seriously though, whats really strange is that since ive started using a chrono ive noticed the amount of hop and actual poi shift correlates directly to extremely minor velocity variations. is this freak coincidence?

 

[C.K]

Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">It's simple, we are not consistent in the pressure we put on the rifle.

1. Bad trigger pull
2. Angles introduced at the shoulder where the rifle moves against
3. sympathetic squeezing or movement with the support hand
4. improper cheek weld with force of your face pushing the rifle to right which causes it to go left
5. not loading the bipod but in fact pulling it backwards

The list of shooter errors is long...

</div></div>

#5
Is the mil not teaching this as proper on some of their rifles? Due to bipod.

 

[sobrbiker883]

Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tburkes</div><div class="ubbcode-body"> The MAIN thing that keeps being forgotten by all of the "experts" on the mathematical formulas is the most important thing, the HUMAN FACTOR, the loose nut behind the trigger.........


Proper application of the Fundamentals Of Marksmanship is what is going to help..........guys hit their targets when the chips are down.

I have never heard Frank, or Jacob say that torque, spin drift, or coriolis effect, don't exist, in fact they'll be the first to tell you that they do indeed exist, BUT, they don't effect the discipline that we are all on this site for enough that it matters in the real world. The FOM are what matter over all the mathematical formulas and have a much greater influence on whether or not you're bullet will hit it's intended target.

</div></div>


With truth like this available I can't believe we're still here.

(Has the OP even been back?)

 

[beezaur]

Re: Recoil off bipod

If I'm doing my calcs right . . .

For a 175-gr, 30-cal bullet going 2550 fps, the bullet's moment of inertia (I) is

I = 1/2 * m * r^2 = 8.87e-8 kg m^2

angular acceleration (a) using a 11-twist barrel would be 1.46e7 s^-2 (radians per second squared)

So the moment M applied to the rifle is
M = I * a = 1.266 N m

or about 11 inch-lbs.

Suspend a 1-lb weight on a rod 11 inches long hanging off the side of your rifle. That's how much torque the bullet applies when it launches, using average rotational acceleration.

Actual peak acceleration comes about 1/3 of the way down the barrel, and is ~3x higher. So peak moment is more like 30 in-lbs.

Scott

 

[Tburkes]

Re: Recoil off bipod

I rest my case. Thank you for reinforcing my comments made earlier.

 

[beezaur]

Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tburkes</div><div class="ubbcode-body">I rest my case. Thank you for reinforcing my comments made earlier. </div></div>

What's that supposed to mean?

You think 30 in-lb is not significant to the shooter?

Why do you think proper form is so important? (The shooter has to counteract all those violent forces.)

I think you don't understand it, so you are dismissing it.

Scott

 

[ArcticLight]

Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: beezaur</div><div class="ubbcode-body">If I'm doing my calcs right . . .

For a 175-gr, 30-cal bullet going 2550 fps, the bullet's moment of inertia (I) is

I = 1/2 * m * r^2 = 8.87e-8 kg m^2

angular acceleration (a) using a 11-twist barrel would be 1.46e7 s^-2 (radians per second squared)

So the moment M applied to the rifle is
M = I * a = 1.266 N m

or about 11 inch-lbs.

Suspend a 1-lb weight on a rod 11 inches long hanging off the side of your rifle. That's how much torque the bullet applies when it launches, using average rotational acceleration.

Actual peak acceleration comes about 1/3 of the way down the barrel, and is ~3x higher. So peak moment is more like 30 in-lbs.

Scott </div></div>


DMCI is that you?

(JUST KIDDING!!!)

All of that and my muscles must be muscle-memory trained because I do not suffer from this issue...

Course did you take the weight of therifle into consideration?

My rifle is like 16lbs loaded..

 

[Lowlight]

Re: Recoil off bipod

I think what he means is you have to weigh the 30 inch Lbs against the force from going straight back... you measure it as if it all goes to the side, which it does not, there also has to be force to the other side the momentum goes in all directions.

How is the force moving forward and backward affecting the sideways number.

 

[beezaur]

Re: Recoil off bipod

The 30 in-lb is just the applied moment (or torque or couple or whatever you feel like calling it).

A heavier rifle will rotate less. A rifle with a full magazine will rotate less. A rifle with a heavier scope will rotate less too.

This is completely separate from rearward recoil. A more powerful cartridge will tend to have more of both, but not always. But rotational effects and rearward motion effects are independent.

How it makes a practical difference to the shooter is the bipod.

If anyone has the equipment, please think about doing the following experiment:

Take a Sako TRG or AI AW, and shoot it with the stock bipod, the one that plugs in just under the barrel.

Then take off that bipod and replace it with a Harris that has a swivel and attaches under the forend on a sling stud or rail adapter. Leave the pivot loose. Don't tighten it with a Pod-Loc or something, just shoot the gun.

Now, does either of these setups cause bipod hop? Can you make the Harris hop? Can you make the stock bipod hop?

If you use crappy form on purpose, can you get either of these to hop? Which is worse?

Scott

 

[Lowlight]

Re: Recoil off bipod

I have all three rifles and they all shoot the same... if I force myself out of position they will hop because they recoil off me.

the difference you are missing is the slop in the bipods, the two you mentioned the TRG and AW Parker Hale have a lot of slop in them, so you can have the rifle move but not the bipod because the force you are explaining stays within the rifle, and doesn't transfer as much. Plus they have a wider leg spread. A Harris is short and stiff, even with the pod loc lose it is still less travel than either of the other two.

But a bad position will cause this... the test you are looking for is a wide front rest with no attachment to the rifle. Will the rifle roll over on its side, and frankly I have never seen it.

The belly benchrest crews use a wide rest up front with a basic rabbit ear on the back, their rifles recoil in a straight line as they also put baby powder on the rest. The rifle does not flip over when the end of the rifle is not supported to the side.

You're working too hard and don't understand how rifles fire instead you revert to the math to explain your point. They don't roll over with 30 in lbs of force...

 

[wksinatl]

Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ArcticLight</div><div class="ubbcode-body">

If I'm doing my calcs right . . .

For a 175-gr, 30-cal bullet going 2550 fps, the bullet's moment of inertia (I) is

I = 1/2 * m * r^2 = 8.87e-8 kg m^2

angular acceleration (a) using a 11-twist barrel would be 1.46e7 s^-2 (radians per second squared)

So the moment M applied to the rifle is
M = I * a = 1.266 N m

or about 11 inch-lbs.

Suspend a 1-lb weight on a rod 11 inches long hanging off the side of your rifle. That's how much torque the bullet applies when it launches, using average rotational acceleration.

Actual peak acceleration comes about 1/3 of the way down the barrel, and is ~3x higher. So peak moment is more like 30 in-lbs.

Scott </div></div>


"<span style="font-weight: bold">DMCI is that you?

(JUST KIDDING!!!)</span>"


I bet not many people get it. I do.........LOL

Keith

 

[Lowlight]

Re: Recoil off bipod

As a ps you're missing the fact that the front of rifle jumps up because the back of the rifle hits your shoulder which lifts the front in the air if you don't support the straight back action... I have yet to hear acknowledge that part of the mathematical equation... the pivot point.

 

[The Mechanic]

Re: Recoil off bipod

like an old six-gun compared to a 1911

 

[Slickrick0999]

Re: Recoil off bipod

I just want to know how I can stop it. I am convinced that it is nothing more than my, as Lowlight says "driving thru the recoil". The reason that I can say that is because I can shoot my suppressor and sometimes manage to do it correctly. The problem is I am failing to understand what to do so that I can practice correct form. I try to allow for the natural POA and line myself up straight behind the gun. I try my best to control breating, although I know I need work here. I stay on the gun and do not change cheek welds. Another area that I am getting better at (still need work) is with the follow thru.
As info, I shoot a bolt action and always off of a bipod. Also, I shoot better from prone than bench.

 

[Lowlight]

Re: Recoil off bipod

Seems to me, some people are not taking the time to watch any of the videos I posted... cause we're not using any recoil managing aids, and we are shooting off a hard surface that should be causing all kinds of problems, yet we aren't having the problems.

Also, the kid shooting left handed is clearly having his rifle jump in the opposite direction the right handed shooters are seeing, which lends one to see how its shooter induced.

The videos are pretty clear, without digging the bipod into the ground, using aggressive feet, etc, the rifles are recoiling straight back and returning to target. It's pretty simply and easy to see.

One thing i was thinking about while hauling rocks around my yard, is that sideways component of the torque as speculated on with such vigor... why then even in the video of Jacob using a suppressor doesn't the rifle appear to twist on the AI spigot bipod which is more free standing ? If you reduce the felt recoil straight back with a suppressor, that should leave a large amount of the sideways intact, however it's not there and yet it's all pretty standard fare being used.

Watch the video, there are clues there...

 

[Tburkes]

Re: Recoil off bipod

Sorry I'm late to the party, work called and I just got in a position to make a comment.

Scott, after your math what I mean is that I'm even MORE convinced that your math doesn't mean jack squat when it comes to putting lead on steel. Once again, 30 inch pounds is lost in the white noise compared to the input the shooter has on the rifle.

Yes, you are exactly correct. I don't understand your fancy math you posted, and yes I completely dismiss it. Ok, I'll admit it, you're a much better mathematician than I am, so what, we're not talking about formulas the add up to 30 inch pounds because it doesn't mean anything to a guy trying to hit a target with a rifle bullet.

So my rifle is going to torque more with a mag with one round in it as compared to a mag with 10 rounds in it? Enough to keep me from hitting my target? You are getting funnier by the post.

I've been on the line when there's everything from a really light weight factory LTR to a 20 pound AIAWSM. When the SHOOTER does what he's supposed to be doing, amazingly, the bullet hits what it's supposed to. We didn't even talk about torque, angular acceleration, or even radians per second squared

I've seen guys shoot with no bipod, just off their pack and hit the target. i've seen them put different bipods on their rifles and hit the target. I've even seen a guy make a shot support side laying on top of a culvert, and the next shot strong side laying in the dirt, and the next shot through a bus window. I can promise you no one is thinking about the 30 inch pounds of torque that's not there when the bipod is off versus being there when it is on the rifle. All they're thinking about is FOM, FOM, FOM. Let's no EVEN cloud the issue with what may happen if for one shot my Pod Lock is tight and then I accidentally make it looser for the second shot, thereby introducing more, or is it less, torque on the rifle. The thought of what may happen makes me just shudder.

I think what is really happening is the theory of PFM. I'd type the whole thing out for you, but it would take too long, so I'll give you the short abbreviated version. PFM, means Pure, F*&%ing Magic. This is the formula I use when there's something happening that I don't know about, and even more, don't care to know, it's just there and I don't need to know the mathematical formula for it to hit the target.

I think you're just spouting this stuff out now just to show off.

 

[Carnivore]

Re: Recoil off bipod

Damn! My head hurts and I'm a P.E.!