Fieldcraft Recoil off bipod

#151
Re: Recoil off bipod

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

We're talking about putting the bullet on the target. Bipod hop is relevant to that, and it is relevant to followup shots (more so).

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">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.</div></div>

Anything that increases the rotational moment of inertia will help stabilize your rifle. Having a fully loaded 20-round magazine that hangs way down will stabilize your rifle against rotation better than having a fully loaded blind magazine that sits right under the bolt. More mass away from the axis of rotation helps stabilize things.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">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. . . .</div></div>

I'm not talking about those times. I'm only talking about the case where there is bipod hop. My whole thesis is that bipod hop has its root cause in torque from the bullet. Control that torque, and you reduce the times where bipod hop happens.

There is a related question of how this affects accuracy. Even when you have no hop, how is accuracy affected? Will you get better accuracy off a better bipod? (Why did AI and Sako design their bipods the way they did?) If you could increase your real-world accuracy from 1 MOA to 3/4 MOA by switching bipods, wouldn't you do that? I would.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I think you're just spouting this stuff out now just to show off. </div></div>

That is really disappointing.

I posted my original reply early in this thread because I feel I know something that would be useful to others. I posted the math so that someone else can check it.

I mean think about this: you are refuting torque from something that is spun up to almost 3000 revolutions per second in about a thousandth of a second. This should not be a controversial issue.

I would love to hear how you guys think bipod hop is generated. By what mechanism do you think a 15-lb rifle is lifted off the ground and moved two feet ahead of the shooter?

Scott
 
#152
Re: Recoil off bipod

Scott, I shot the best group I've ever shot at 100 yards the last time I was down at Rifles Only.

I was laying on a wooden deck, using an Atlas bipod with the rubber feet that will roll if you push forward very much at all, and one of my rear bags. I was using some new ammo that we had for testing.

I had five rounds in the mag and never pulled my head off the rifle, I was concentrating on the FOM for every shot. Every shot returned to the same place after recoil, within a few tenths of a mil from the aiming point. The group was one little .30 caliber hole that was wallowed out a little bit. I do know how to shoot a rifle and usually have a fairly respectable showing at the matches I shoot. I said usually, sometime I totally screw the pooch, but it's because I haven't been practicing the FOM. Funny how I keep coming back to this isn't it?

In this case real world accuracy is a five round group that is barely wider than a .30 caliber 175 grain Sierra Match King bullet. Are you telling me that suspending a Cinder Block underneath the rifle would have made the group smaller still, because it would have increased the rotational moment of inertia and better stabilized the rifle?

If you're shooting 1 moa groups out of a custom rifle then you need to get away from the computer and slide rule and work on the loose nut behind the trigger.

3000 revolutions per second. So what, white noise, concentrate on FOM.

You're quote, "By what mechanism do you think a 15-lb rifle is lifted off the ground and moved two feet ahead of the shooter?"

WHAT!!! Scott, put down the crack pipe man. I've never had my rifle lifted off the ground and jump two feet ahead of me when I've fired a round. Have you even watched any of the video's that Frank has posted of a rifle being fired? Have you ever fired a rifle? Come on now this is getting crazy.
 
#153
Re: Recoil off bipod

Scott, you seem to have strayed again, and again, bipods' don't hop, poor shooting positions cause the front to lift... The front of the rifle lifts off the ground because of the recoil at the shoulder, not because of the torque in the barrel.

Try this for math, figure the angle, because that is what you are looking, the bouncing off of the rifle at an angle introduced at the shoulder. The shooter has four points of input, the firing hand, the support hand, the shoulder and cheek, you don't think one of those improperly applied can be the root cause ?

I can see impacts on paper at 100 yards, actually see the bullet hole appear without losing sight picture... I am 5.2" 130lbs shooting increasing shorter barreled rifles using the same equipment as everyone else. My bipods don't hop...

What you're proposing is trying to fix a fundamental error with equipment.

Either you get it or you don't...
 
#154
Re: Recoil off bipod

Five feet two, my ass. Maybe in your high heels...
laugh.gif
 
#155
Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tburkes</div><div class="ubbcode-body">
You're quote, "By what mechanism do you think a 15-lb rifle is lifted off the ground and moved two feet ahead of the shooter?"

WHAT!!! Scott, put down the crack pipe man. I've never had my rifle lifted off the ground and jump two feet ahead of me . . . </div></div>

When the bipod hops, it usually lifts off the ground. The bipod is about two feet ahead of the shooter. The movement is relatively smaller (an inch if that).

Scott
 
#157
Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">
Try this for math, figure the angle, because that is what you are looking, the bouncing off of the rifle at an angle introduced at the shoulder. The shooter has four points of input, the firing hand, the support hand, the shoulder and cheek, you don't think one of those improperly applied can be the root cause ?</div></div>

Firing hand does not supply sufficent force to cause bipod hop. The cheek pushes the wrong way.

Support hand and shoulder are candidates. They can and do cause lots of problems. They undoubtedly contribute to bipod hop.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">My bipods don't hop...

What you're proposing is trying to fix a fundamental error with equipment.</div></div>

No, what I'm doing is explaining a problematic rifle behavior. The fix you are talking about is shooter form. I'm not saying that won't fix the problem. I'm saying equipment plays a part in it.

Suppose someone comes to you who is shooting a rifle with an inconsistent trigger that is set at 12 lbs, and the trigger is affecting their shooting. Are you going to rail on them about trigger control and tell them to suck it up and deal with the trigger? Or are you going to teach them proper trigger control *and* tell them to go see a smith about a better trigger.

Not everything is purely the shooter. Sometimes equipment is a contributor.

Scott
 
#158
Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tburkes</div><div class="ubbcode-body">Have you ever fired a rifle?</div></div>

No, but I read a book about a guy who did.
smile.gif


Look, sorry if I am being terse. I'm way over serious sometimes. You're right to be skeptical. You guys are a hard crowd, but I can respect that.

Scott
 
#159
Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: beezaur</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tburkes</div><div class="ubbcode-body">
You're quote, "By what mechanism do you think a 15-lb rifle is lifted off the ground and moved two feet ahead of the shooter?"

WHAT!!! Scott, put down the crack pipe man. I've never had my rifle lifted off the ground and jump two feet ahead of me . . . </div></div>

When the bipod hops, it usually lifts off the ground. The bipod is about two feet ahead of the shooter. The movement is relatively smaller (an inch if that).

Scott </div></div>

I don't have a dog in this hunt as my .308 model 700 w/a Harris seems to stay put as well as my 300wm, when I'm behind it correctly.

But I do have a question, please tell me why my M14e2 on Full Auto does not hop around, nor does the M60. Is there a major diff between them and a lowly bolt stick? They both, have bipods and are 7.62x51?
I don't have near as much time behind a bolt .308 but I've lots of time behind the others, so learn me.
 
#160
Re: Recoil off bipod

OK. So I duct taped a 29" stick to the side of my 20" 308. As close to the throat as I could guess. I decided on 29 instead of 30" cuz I figgered the stick had to weigh somethin right? And I wanted to be all scientific. Next I duct taped a 1 lb lead ingot to the end of the stick. I squirted a 168 SMK at about 2650 out of her with free recoil off a Harris SBR off of a concrete bench. I used a 110 volt, 2 position, 36" shop fan to keep the 80% humidity (and skeeters) of the barrel. Didnt wanna mess w/ POI.
Much to my amazement, I was only off 3 MOA left at 300 after proper follow through.Thats like 2 MOA less than without the stick and weight.
So my questions are.......

1- Should I add an 1/4 lbs of weight?

2- Or should I add 2-3"s to the stick?

3- How much should I charge to manufacture my creation once I get the bugs worked out. Keep in mind I will be using camo tape on the final assemblies.

Thanks in advance.
 
#161
Re: Recoil off bipod

Wrong_internet.jpg



FOM trumps theory every time, and Lowlight's adaptation of the FOM as applied to shooting off a bipod has eliminated my rifle jumping off target.

For all other arguments on the topic, please refer to the second line of my signature.........
 
#162
Re: Recoil off bipod

HaaHa! Terse, as in, sparing in the use of words?
smile.gif
Hardly, you've been more than free with your theories and formulas, the vast majority of which don't mean anything in the real world of tactical shooting.

In addition to everyone else here who gave sound advice on bipod hop, I gave you a perfect example of a personal experience and still you refuse to believe anything you've been told. You let real world examples go in one ear and out the other without retaining anything on the way through. That's ok, just keep believing it.

I still put it down to PFM.

I've received two PM's asking what I mean when I say FOM.

I'm sorry I wasn't clear when I started using that, FOM is short for, Fundamentals Of Marksmanship.

If you'll do lots of perfect dry fire practice and, concentrate on the FOM, you'll be amazed at the progress you can accomplish in your shooting skills, and you'll never even have to think about rates of acceleration, rotational moments of inertia, axis of rotation, angular acceleration, or even torque.
 
#163
Re: Recoil off bipod

Tburkes,

I can't believe you even bothered to respond to this shit.

I know, it's because you are a nice guy and trying to help.

You and Franks response is sufficient to anyone who understands English. Anything else is a waste of time.

What happened to the simple understanding that for any action (bang), there is a reaction (recoil), and that proper recoil control/management through fundamentals of marksmanship equal bullet on target.
The better the control of recoil, the less movement of the system, as seen by the child (at 60 pounds) shooting both barrels of the 12 gauge being knocked to the ground while grandpa (at 210 pounds) can do it all day and stay standing on his feet.

Bipod hop is simple, the shooter does not have control of his rifle.

Following the fundamentals gives you a degree of control, not always guaranteed based on the weight of the rifle versus the strength and experience of the shooter.

The biggest problem I find is the empty space between the ears.
 
#165
Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Gunfighter14e2</div><div class="ubbcode-body">I do have a question, please tell me why my M14e2 on Full Auto does not hop around, nor does the M60. Is there a major diff between them and a lowly bolt stick? They both, have bipods and are 7.62x51? </div></div>

I'm not familiar with those weapons at all, but here are some things that can make a lot of difference:

1) auto/semiauto mechanisms have a lot of moving parts. Even if bipod hop or some other problematic motion was started, the motion of those parts could undo that action. Obviously an engineer designing a machine gun would not be doing his job if the design allowed bad motions under recoil. Things have come a long way since the Tommy gun.

2) Not all bipods will cause bipod hop. I don't know anything about those bipods you are referring to, but it could be that they are not prone to it.

This is not a problem that every weapon will have.

Scott
 
#166
Re: Recoil off bipod

Well, not that you guys particularly care, but I found my old accelerometers runs.

They are from 2005 and use a Ruger M77 MkII Target in .243 Win. I was using either a 95 or 105-gr bullet (did not find my notes).

The Accelerometers are Vernier brand 1-axis and 3-axis linear accelerometers (i.e., they measure linear not angular acceleration). Student grade stuff, but I did go through a fair amount of calibration from low to high frequency and they checked out pretty well. Who knows what luck you'd have buying the same thing today for this use, but my particular specimens checked out well before and after use. So my data should be relatively free of instrument dynamic effects, hysteresis, and the like.

They were fixed to the stock on the left side next to the recoil lug, one accelerometer for each run. I did about one run a day, must have been after work.

I also looked through my library and found some similar work by a guy named Vaughn, in his book <span style="font-style: italic">Rifle Accuracy Facts</span>. The only thing I found relevant to the present discussion (I have not read the whole book) was on p. 168, where he talks about torque from spin-up and its affect on accuracy. By his admission, that discussion is a coarse approximation. He talks about a freely recoiling rifle and how shot-to-shot variation in torque (due to velocity variation I suppose) has an immeasurably small effect on accuracy. I would agree.

Vaughn does not address a rifle whose motion is partly restricted, as is the case with a pivoting bipod, but he does discuss the effect of torque on bullet impact for a .270 Win shooting a 90-grain bullet with 15 inch-lbs of torque (average). He calculates a small, but measurable impact displacement for that relatively unrestricted recoil case. Again, he does not get into more severe cases like bipod hop.

The point is he comes up with measurable rifle movement resulting from spin-up torque.

I'll post my data in a few minutes.

Scott
 
#167
Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: beezaur</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Gunfighter14e2</div><div class="ubbcode-body">I do have a question, please tell me why my M14e2 on Full Auto does not hop around, nor does the M60. Is there a major diff between them and a lowly bolt stick? They both, have bipods and are 7.62x51? </div></div>

I'm not familiar with those weapons at all, </div></div>

M14e2, fires from a closed bolt
dbs10_011.jpg


M60, fires from an open bolt.
500px-M60.jpg

 
#168
Re: Recoil off bipod

So here is one of my better plots showing the front-back motions of recoil.



Measurements were taken every 0.0003 s (0.3 ms). There are three distinct features: the lump at 0.0132 to 0.0174 s, the big spike from 0.0174 to 0.0222 s, and the large tail that tapers off.

The first small lump is the firing pin lurching forward. So lock time is pretty slow. It takes 4.2 ms for that pin to fall. You can see acceleration reverse for one reading just as the pin hits the end of its travel. Keep in mind this is from movement measured on the stock. The firing pin's motion actually caused the whole rifle to move for 4.2 milliseconds.

The big spike is from the powder and bullet slamming forward and down the barrel. This is the major recoil impulse. It lasts 1.2 ms until the bullet exits. Then you have some reduced rearward acceleration from gas venting out the muzzle.

The big tail where acceleration has switched from negative to positive is when the rifle (which is moving now) begins to be decellerated by my body. The wiggles are the result of things like barrel vibrations.

You'll notice a small variation in measurements at the very start of the plot. That is the level of noise for this particular instrument (pretty small).

Scott

Thanks to ImageShack for Free Image Hosting
 
#171
Re: Recoil off bipod

Now here is a plot of a shot with no bipod hop.

recoil2.png


Pink is front-back, like the other plot above. Blue is side-to-side. This 3-axis accelerometer is a lot noisier than the 1-axis that was used in the post above, but you can still see the same general features. "Zero" is not exactly at 0.0 on the scale because the setup was not perfectly level. So there would be a constant correction made to compensate for that. This is just raw data straight from the instrument.

Notice that the blue line oscillates around zero. That means the rifle had plenty of vibrations, but on the whole the rifle did not move laterally.

Here is a shot showing bipod hop. Note the blue line showing acceleration all one way. That is lateral displacement.

recoil3.png


Scott
 
#172
Re: Recoil off bipod

I have to get to work today, so I don't have time to finish posting the stuff I wanted.

I will summarize it though:

Right at peak bullet acceleration there is a strong rotational acceleration that rotates the rifle counterclockwise. This usually lasts only a while, as the rifle is stopped in its rotation by the bipod (Harris mounted on a sling stud under the forend). Then lateral movement takes over. In a nutshell, the bullet spins the rifle, but the rifle can only spin so much due to the bipod. Then the movement becomes lateral movement because the bipod forces it.

Not all bipods will cause hop. The rifle wants to rotate about its center of mass, which usually is just under the barrel. If the bipod pivot coinsides with that natural axis of rotation, all is well. But if the bipod forces rotation about a different axis (its own), then you can turn rotational motion into translational motion and you get bipod hop.

I believe weapon designers know this, and design their own bipods (AI, Sako, M60 machine gun, etc.) to minimize the effect. But that is not an option for aftermarket manufacturers like Harris. Harris has to make do with a mounting point that is available: the sling stud. Not the best, but they deal with what they have. You can compensate with things like Pod-Locs and better form, but the fundamental problem (pivot in the wrong place) is still there.

Scott
 
#174
Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">Pretty pictures.

Now go back to pg1 or pg two of this thread, both Lowlight and myself have posted videos of proper FOM defying the laws of physics. </div></div>

You're not defying the laws of physics. You're showing how to correctly compensate for the violence of recoil.

Anyone here shoot bows? Some bows will throw an arrow way off with the slightest hitch in form. They can be shot well, but everything has to be perfect. Other bows will put the arrow pretty much on target even if you are sloppy. The archery term for the easy-to-shoot bows is "forgiving."

That is the kind of thing I am talking about here: a rifle bipod that is forgiving.

Scott
 
#175
Re: Recoil off bipod

Last one.

recoil4.png


This shows front-back (pink), lateral (yellow), and vertical (blue) acceleration. I should note that the previous two were noisy and had low accelerations because it was a very hard hold.

Anyway, notice that the lateral and vertical accelerations are pretty quiet during the firing pin's travel. Not much is happening during that time except the rifle is coming straight back.

Then, bam! at 0.0237 seconds you see a jump in vertical acceleration where the accelerometer jumps down. This thing is about as big as a small walnut, fixed on the stock just left of the recoil lug of the action. A downward lurch on the left side of a rifle resting on a bipod means only one thing: counterclockwise rotation. Now things start getting interesting.

The lateral trace (yellow) starts accelerating to the left at 0.0240 s just as downward acceleration hits a hitch and levels off. This is the slack on the bipod taken up and forcing some rotational motion into translational motion. The rifle is trying to keep rotating, but force is being directed down that right leg to solid ground and it can't. So things start to move sideways. Notice the stengthening lateral acceleration until the bullet exits at 0.0252 s. That's torque from the bullet trying to rotate the rifle, but ending up dumping energy into lateral movement.

After the bullet exits, the rifle is moving both laterally and rotationally. So the acceleration traces are not so simple to interpret. Suffice it to say the rifle is well into bipod hop at this point.

By the time the bullet exits the barrel, the muzzle is moving laterally at around 0.03-0.06 m/s, or about 1-2 inches per second. A bullet leaving that muzzle will also have the same lateral velocity, and will hit the target off from where it would without. There is also a small additional effect from the rifle being pointed slightly to the left when the bullet exits.

This is with a .243 that weighs around 14 lbs shooting a mild-ish load. A .308 will show more of the same.

Scott

P.S. Horizontal axis is time in seconds. Vertical is acceleration in meters per second squared (gravity is 9.8 m/s^2).

Thanks to ImageShack for Free Image Hosting
 
#178
Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Wonder what it would look like if you actually knew how to shoot... that is the Million Dollar question. </div></div>

I do okay. There are many better shots, but I hold my own. I could only measure what I had at the time, just me and my .243.

I forgot why I was measuring recoil then, but I don't know that it was to figure out bipod hop. Most of the runs had variations in holding hard or weak.

Funny what you learn when you start fiddling around and measuring stuff.

Scott
 
#179
Re: Recoil off bipod

Funny how you haven't considered what happens during free recoil with a bipod, how it bounces and vibrates, which is why it might be a good idea to not use free recoil with one.

I'm betting your less than scientific approach and even less understanding of a rifle might have actually caused more of a reading than would ever be present.

Have you seen this: Bugholes from Bipods

he shoots one hole groups with a bipod... so who is right here, YOU or guys successfully employing the precision rifle that doesn't hop.
 
#180
Re: Recoil off bipod

<object width="425" height="350"> <param name="movie" value="http://www.youtube.com/v/79bWH6d2iuo"></param> <param name="wmode" value="transparent"></param> <embed src="http://www.youtube.com/v/79bWH6d2iuo" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"> </embed></object>

Note the recoil is not ripping out their hand to the side but straight back off the shoulder. especially note the action at 1.21 seconds
 
#181
Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">
Have you seen this: Bugholes from Bipods

he shoots one hole groups with a bipod... so who is right here, YOU or guys successfully employing the precision rifle that doesn't hop.
</div></div>

I've seen it. I shoot ~1/2 MOA groups in calm weather at 600-800 yards off my bipod (a Harris) because of good advice from him and others. That's about what my .243 is capable of. I've got a .280 AI that is more accurate. Last time I shot it I did a 1.5" 5-shot group at 620 yards.

As if that has any bearing on bullet torque.

What is it, I don't have enough posts so you don't think I can shoot?

Maybe you should pick up a copy of Vaughn's book. I mean, I realize this isn't your area of interest like it is mine, but he does a lot of the same kind of thing. Lots of accelerometer info in there, and some really good explanations of things like bullet core failure in the barrel and flexing under recoil.

Scott
 
#182
Re: Recoil off bipod

I don't need to pick up anything clearly by my video I can shoot on any surface and my bipod doesn't hop, or come off target... I don't think you can say the same.

As well I will offer you a free spot at the Fall Bash,however if you don't place in the top 10 you have to pay double the entrance fee, or at least you have to do this in front of people, that is shoot a sub moa group at distance close to your claims.

Personally I think you are the most dangerous kind of person, you know just enough to be dangerous and not enough to understand what you are seeing for yourself. Using charts and graphs that will show anything you want to prove a point, yet the point is invalid in the real world of shooting when things are done correctly. How is it that allowing the rifle to bounce around in free recoil doesn't cause movement in every direction like your graph shows. A tiniest bit of the proper support can and probably does change it completely for the better.

A guy with a meter on a rifle he doesn't understand... the possibilities are endless.
 
#183
Re: Recoil off bipod

Lowlight,

If I have insulted you in some way, I apologize.

I said I have a high regard both for your shooting and your instructing, and I meant that. You really are very good at what you do.

Scott
 
#184
Re: Recoil off bipod

If you insulted me personally I wouldn't have offered you a free spot to the Bash, provided off course you can back up your claims.

I just don't think you realize what you are doing when you let a free recoiling rifle bounce around then claim to scientific proof to a phenomenon as too why someone is experiencing lateral recoil. Its dangerous, as you provide fuel to a fire.
 
#185
Re: Recoil off bipod

So, how was the rifle being shot while these graphs were created?

If it was being shot by you, all they really do is prove the point that it is the shooter. Any lateral movement recorded could be just as much caused by the shooter as by rotational tourque.

Any shooter error will register on your accelorometer. That is a very un scientific approach to collecting data. It will help show the shooter's weakness though.

For your data to support any claim at all, it needs to be recreated exactly as before. but in a vise. And then it needs to be created exactly with a freestanding rifle, i.e. not support, no backstop or "sholder" and no forces acting upon it in any way.

I am interested to see the results.
 
#186
Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gugubica</div><div class="ubbcode-body">So, how was the rifle being shot while these graphs were created?

If it was being shot by you, all they really do is prove the point that it is the shooter. Any lateral movement recorded could be just as much caused by the shooter as by rotational tourque.

Any shooter error will register on your accelorometer. That is a very un scientific approach to collecting data. It will help show the shooter's weakness though.

For your data to support any claim at all, it needs to be recreated exactly as before. but in a vise. And then it needs to be created exactly with a freestanding rifle, i.e. not support, no backstop or "sholder" and no forces acting upon it in any way.

I am interested to see the results. </div></div>

The rifle was shot by me from prone, with form variations that I recorded in a notebook that I could not find.

The point of my experiments was to measure how the rifle recoils against the human body. As I said, I don't remember the precise goals, but it had something to do with a hard hold versus soft and things like that.

I've done a lot of similar work with archery equipment. This work with rifles grew out of things I learned with the bow.

The free recoil thing would be helpful for pinning down rotation, but again I wasn't looking for rotation 5 years ago when I did these experiments. If I pick up the project again, I will certainly incorporate that.

The overall issue I was studying, both with the bow and the rifle, is the ergonomics of shooting. I have long felt that accommodating the shooter's body will produce better accuracy. I was trying to put some numbers on the actual motion of the rifle during firing.

To that end, the experiments succeeded reasonably well. There is a lot going on when the shot breaks, some of which can be difficult to tease out. But it did illuminate quite a bit.

Were there things left undone? Sure. Knowledge is never complete. It seems like every time a person endeavors to find something out, they end up uncovering more questions that remain to be answered. This was no different.

You can spend a lifetime learning about something as simple as a bolt action rifle, and never get halfway there. There is much to learn and more to master.

So I have my few rifles and 800 yards of field that I shoot over. I do what I can with it. I would like to go to TX and get that training someday, but other obligations have to come first.

Scott
 
#187
Re: Recoil off bipod

Once I was digging a moon hole, an hit rock. It was such a perfect place for it, 270* of natural protection, with an out.
I over looked the sound I was making trying to dig that rock.
 
#188
Re: Recoil off bipod

Another video of a bipod not hopping, TBurkes shooting from an alternate position on a big rock... note the bipod in the very beginning

<object width="425" height="350"> <param name="movie" value="http://www.youtube.com/v/A-E9bs65kOY"></param> <param name="wmode" value="transparent"></param> <embed src="http://www.youtube.com/v/A-E9bs65kOY" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"> </embed></object>

You only need to watch the first minute to see what proper form does for the rifle.
 
#190
Re: Recoil off bipod

Not the bipod, but the shooter changing position.
Didn't hear ring for hit on first target.
Everything in front of the trigger is already loctited.

Behind is not.(weakest link is where?)

Terrain looks sheltered by the trees.
Rolling hills remove that comfort zone.
 
#191
Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Another video of a bipod not hopping, TBurkes shooting from an alternate position on a big rock... note the bipod in the very beginning . . .</div></div>

It looks locked down.

Scott
 
#192
Re: Recoil off bipod

BZ,
Do you need help with cameras?
With your paper, you should know more.
Please help us with our problems, instead of trying to be little us.

What is the range of a rubber band using "Dynamics"

Hole for bushing.
.375/.376

Bushing .378/.379

id .250/.251

Mating part, .249 /.250

Will it spin freely?

Lose the numbers, help with practicle.
A pig in the mud still enjoys it, some get annoyed.

I can give more examples if you want.
 
#193
Re: Recoil off bipod

BZ = me, I assume.

I'm not trying to belittle anyone.

It's frustrating. Frank says you can get rid of bipod hop with proper form. I say yes, you can get rid of bipod hop with proper form. Franks says dammit, stop that nerd shit, you can get rid of bipod hop with proper form; see, here's all these guys with great form whose pods are not hopping. It's just this endless miscommunication.

I'm not trying to say how to get rid of bipod hop. I'm trying to point out one mechanism at work when it happens. We do all agree that it happens sometimes, right? Has anyone else got an explanation as to why?

I don't own a video camera. The stuff I am measuring is too fast for a standard camera anyway. If there is a cheap high-speed camera somewhere, I would be interested. I have looked into it, they were thousands of dollars when I checked last.

Scott
 
#195
Re: Recoil off bipod

What's frustrating is you endlessly saying that bipod hop has more of an effect on accuracy than the input of the shooter.

You've been told, and shown, that any bipod hop that effects accuracy is due to a shooter not using the proper fundamentals of marksmanship.

When the proper fundamentals of marksmanship are employed, any bipod hop is so small that it doesn't mean jack in the exterior ballistics performance of the round.

What you are doing is clouding the issue for any new shooters who are trying to read and learn what the most important things to consider are when starting out in the long range shooting arena.

The most important things a new shooter should think about when starting out is employing the PERFECT fundamentals of marksmanship in his dry fire practice. He should dry fire every chance he gets using perfect form. This will transfer over to the range when he starts shooting live rounds.

The guy DOESN'T need to be worrying about all the formulas, theories, graphs and charts you've been trying to convince people are important to shooting.

"I'm not trying to say how to get rid of bipod hop."

This is the first time in this whole thread, that I've read, where you say you're not trying to get rid of bipod hop and that you're only slinging theory about what happens when a round is fired. Your experiments are so flawed it's funny, you know why, it's you, the human factor. You can't get the same exact readings from one round to another with all those gauges and meters, because you can't have the exact same hold, heart rate, grip pressure, lung pressure, etc. etc. You would have to have the rifle mounted in a machine that could be zeroed from one round to the next in order to have good data to be able to prove...what? Not a dang thing that has ANYTHING to do with sending a round down range when a human is what is pressing the trigger to the rear.
 
#196
Re: Recoil off bipod

beezaur,

Digging a hole deeper, well not make it easier, to claim out of.
I made referance to the M14e2 an M60 for a reason, they are both 700yd plus guns, in full auto. Now as a old shooter, of both, I know for a fact you don't hose a 700yd target in FA with improper shooting form. I thought you would understand or research that fact but I was wrong, which is not the first time nor will it be the last.
Next time I'll be more to the point.
 
#197
Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tburkes</div><div class="ubbcode-body">What's frustrating is you endlessly saying that bipod hop has more of an effect on accuracy than the input of the shooter. . . </div></div>

I never said that. I have never in my life held that opinion, and I do not hold it now.

Scott
 
#198
Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Gunfighter14e2</div><div class="ubbcode-body">
I made referance to the M14e2 an M60 for a reason, they are both 700yd plus guns, in full auto. . . .</div></div>

Those weapons are totally outside of the scope of my claims and the work I have done.

My work was with a .243 Win. bolt action rifle and a Harris S bipod. My work is only applicable to bolt action rifles with that style of bipod. So my findings are relevant to something close to that in power, like a .308. It is not directly relevant to a .22 rimfire, and it is not directly relevant to a .408 Cheytac.

Actions with moving parts are totally different beasts. Nothing I have done is more than tangentially relevant to a machine gun. The work I did 5 years ago was utterly and completely unconcerned with such weapons.

My claim is and has been this: with a bolt action rifle using a pivoting bipod like a Harris, when it does produce bipod hop, torque from the bullet is the root cause.

Now, there are a variety of ways to reduce or eliminate bipod hop. You can use good form. You can use a rigid bipod (or make it rigid with a Pod-Loc). You can use a different geometry that is less affected.

Scott
 
#199
Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: beezaur</div><div class="ubbcode-body">The physical reason this happens is because the rifle twists in response to the bullet being spun as it travels down the barrel.

The rifle twists counterclockwise, causing the bottom of the forend to move right. But the rifle is on a bipod, so it can't really move right (right hand bipod leg stops it). So the end result is that the rifle twists anyway, kicks off of that bipod leg, and launches itself to the left.

The effect is magnified by having a lower bipod pivot. That's why some bipods have their pivots just under the barrel.

There are various other things that will cause the effect to be reduced, but when it happens, that is the reason.

Scott

P.S. Shooting off the ruck allows the forend to rotate in place. No bipod leg to launch off of, so no jump to the left. (Sometimes simpler is better.) </div></div>

This was my original claim. I made this claim because I have hard data to back it up, some of which I posted.

Scott
 
#200
Re: Recoil off bipod

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tburkes</div><div class="ubbcode-body">You would have to have the rifle mounted in a machine that could be zeroed from one round to the next in order to have good data to be able to prove...what? Not a dang thing that has ANYTHING to do with sending a round down range when a human is what is pressing the trigger to the rear. </div></div>

You are exactly right.

There is nothing to be gained by measuring the acceleration of a clamped rifle. There won't be any. It's clamped.

That is why I measured the rifle in recoil with a human operator. If you want to know how a rifle recoils against a human, then you have to measure a rifle recoiling against a human.

We also agree that good form helps bipod hop.

Scott
 
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