Advanced Marksmanship Angle of Arc?

[Sterling Shooter]

I've come to believe minimizing the rifle bore's inconsistent angle of arc while executing the firing tasks, through proper control of the rifle, is the most important thing to good shooting, after the fundamentals have been mastered. I believe this is indeed the SECRET to getting the best results. I also think some of the most modern rifles, like the Barrett 98, help a shooter get a consistent angle of arc, by minimizing the degree of the arc. Yet, I find it interesting that there is very little information out there on this topic. I have seen very little on this concept outside of some very obscure texts from the USAMU which have used the terms "angle of arc", as well as "recoil resistance". I wonder if any here have seen this topic discussed elsewhere. I also wonder why something so clear as to effect outcomes is not a part of modern marksmanship discussion.

Sinister recently brought to our attention a 2011 UCLA study on what is important to good shooting. I read this study and concluded angle of arc was addressed as an autonomic skill.

At any rate, I'd like to unwrap this concept. Perhaps there are some folks here who have a thought about it.

 

[Topstrap]

Re: Angle of Arc?

Always interested in learning more about this game but even though you asked about "angle of arc" and I think I might know what you are asking about is there a way to put it in simpler terms? I've found that anything that affects a rifle shooting accurately at long distances is compounded when using our short barreled long range pistols due to more gun movement and slower velocities which makes follow thru that more important.

Know we don't agree sometimes on the way we approach the way we shoot our guns but I also pay attention when I think I can learn from someone and see if it will benefit me. When you start breaking it down as to what affects that bullet exiting a barrel and hitting a distant target it's amazing how many really small things can affect it.

Topstrap

 

[Greg Langelius *]

Re: Angle of Arc?

Are we discussing muzzle flip?

Please be less obscure.

Greg

 

[Greg Langelius *]

Re: Angle of Arc?

If we are, then yes; I've thought about it a lot.

POA is simply a device which establishes a starting alignment/reference point for system's entry into the entire shot cycle.

Taken backwards, the bullet exits the bore along an axis which is the product of some complexity involving force and response. This axis gets derived from recoil and the body's response to that recoil.

When we build our shooting position, not just the pose is important, the muscles tension and joint/pivot relationship is also critical to guiding the muzzle through that recoil cycle. If we alter any part of it, the system will be in a different alignment at the instant were the bullet gains its freedom. For any application absent a rail gun, the body must be considered as a flexible gun carriage.

I think that LL's emphasis on body alignment is critical to addressing this issue.

Greg

 

[Topstrap]

Re: Angle of Arc?

That is what I was assuming but didn't really understand it in a simpler way. Shooters have worked to minimize movement either thru heavier guns, modified stocks, muzzle brakes, correct positioning of their bodies and others probably without knowing why they are doing it other than it helps with accuracy.

We've worked with this but didn't know there was a fancy term for it with our LR pistols. They are similar to shooting a large caliber round in a lightweight rifle with lots of barrel movement, slower velocities and an increased "angle of arc" which I'm assuming is the arc from being straight at the target before the shot and the arc that it's at when the bullet actually exits the barrel? Minimizing that arc reduces the affects outside forces come into play and usually increases accuracy?

If this is so, then proper shooting technique to minimize that arc shot to shot is an absolute necessity for accuracy at distance. We've experimented a LOT with finding what minimizes that on our pistols and find the same applies to our rifles but to a far less degree. We've slowly modified and added brakes, heavier rear grip stocks which change our pivot point the gun recoils from which reduced the rise which reduced the "angle of arc"? Whatever it is, each change has helped accuracy. We are limited as to what can be done to the firearm so a more refined technique is needed to maintain accuracy with our increased "angle of arc".

If this is what you were meaning then we have all seen a basic result of that when we see a shooter that can shoot nice tight groups with a heavy barreled small caliber target rifle. But then hand them a 300 Weatherby in a sporter weight barrel and most times they will be using up a lot of real estate around the target although it has proven to be accurate with a more experienced shooter. Poor technique and an increased "angle of arc" the cause? We always just say less experience and the shooter is flinching but Sterling is bringing up specific topics that do show how specific things affect how accurate we shoot and what can help the shooter and their gun become a team instead of individual players.

Breaking it down to these specific things may seem trivial but these are the things that separate the good shooters from the ones that place near the top of every match and can shoot whatever you put in their hands. Hope this is along the lines of what Sterling was asking about, not knowing the correct terminology in layman terms can be confusing to me but I think threads on the fine points can be helpful. If I pick up enough information to add even one more target at a match then I feel it's been a lesson well learned.

Topstrap

 

[Jaeger308]

Re: Angle of Arc?

I’ll jump in on this one; I think “angle of arc” is referring to what is known as radius of recoil. With some handguns recoil is snappier than with others, this is due to the radius distance from hand position and design to the force of recoil. Take this to rifles, if a shooter has poor position and free recoil the muzzle will move, achieving straight back and hold hard is the goal with rifles with front support. Put your shooting jacket on and sling up that becomes different in that sling tension holds the rifle from free recoil and shooting position in place.

 

[Topstrap]

Re: Angle of Arc?

I made up this quick little clip showing what I think Sterling was talking about. I know, another clip of these LR pistols but it's showing what occurs with rifles but is way more apparent with these guns. Both guns are very accurate but the first one is a lot harder to shoot well due to the movement or more "angle of arc".

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The better a gun is set up the less proper technique is apparent to good shooting. Better technique can overcome poor rifle design but combine the two and that is what makes for super accuracy and that is the goal everyone strives for.

Maybe I'm way off left base but thinking I'm thinking properly what Sterling is thinking.

Topstrap

 

[Graham]

Re: Angle of Arc?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Topstrap</div><div class="ubbcode-body">I made up this quick little clip showing what I think Sterling was talking about... Both guns are very accurate but the first one is a lot harder to shoot well due to the movement or more "angle of arc".</div></div>What that video primarily shows is a difference in technique. Little of that applies to rifle shooting: You don't hard-hold a LR pistol. <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sterling Shooter</div><div class="ubbcode-body">I'd like to unwrap this concept.</div></div>Then perhaps we should define it first.

 

[Topstrap]

Re: Angle of Arc?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Graham</div><div class="ubbcode-body">What that video primarily shows is a difference in technique. Little of that applies to rifle shooting: You don't hard-hold a LR pistol.</div></div>

I disagree with you on that because it does apply to rifle shooting since I don't hard hold my LR rifles either but I'll quit trying to show that a lot of what applies to rifles also applies to these but will not keep trying to relate one to the other.

Topstrap

 

[Graham]

Re: Angle of Arc?

My point: That the lack of a stock equates to a difference in effective technique with regard to recoil management.

 

[Topstrap]

Re: Angle of Arc?

I see what you are saying but the thread I thought was "angle of arc" and how recoil management and gun design affects it. We've had the same issues to resolve but on a larger scale. Still have to have proper position, and also how heavier, better designed stocks, barrels and grip placement affect this. The shoulder stock makes it easier with cheek placement and shoulder tension/placement so it is the same based on that but with just a few different adjustments.

Not all that different overall just some differences in other contact points. Maybe I missed what the proper term "angle of arc" is and how it relates to shooting but any change in barrel angle while the bullet is going down the barrel would have the same affect during the shot? I do think that certain disciplines rely more on equipment rather than technique slightly and also it can be the other way around depending on what type of position and competition they are used in. When you combine both then you generally are near the top of the win list.


Either way, I'm paying attention even if it don't apply to my short guns.

Topstrap

 

[9H_Cracka]

Re: Angle of Arc?

I listened to a lecture from Bryan Litz FTF last week. Something else to stick in your POI shift pipe and smoke for a while - pressures on the rifle effect not only where the muzzle is when the bullet leaves the barrel, but also the VELOCITY at which it leaves. He has been able to repeatably document how rifle pressure can effect the velocity on the order of 20-30 FPS.

We all know what 20-30 FPS differences look like at 1000 yards....

Couple the two and you can have some major POI shifts from technique.

 

[TiroFijo]

Re: Angle of Arc?

A normal sniper rifle in 300WM with a heavy load would have a free recoil velocity in the order of 8.5 fps. I don't see how a "hard vs soft" hold could generate a 20-30 fps difference in muzzle velocity...

 

[9H_Cracka]

Re: Angle of Arc?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TiroFijo</div><div class="ubbcode-body">A normal sniper rifle in 300WM with a heavy load would have a free recoil velocity in the order of 8.5 fps. I don't see how a "hard vs soft" hold could generate a 20-30 fps difference in muzzle velocity... </div></div>

Post your instrumented test results please and we can all "see" what they say. At this point I trust Bryan not to be fibbing about what his instrumented testing produced.

 

[marduk185]

Re: Angle of Arc?

oh i thought you meant me angle o me dangle....sorry

 

[Sterling Shooter]

All,

It seems to me that the word "consistent" is often used to describe what the position should be; however, the consequence of not making the position consistent is sometimes dismissed when the shooter's mindset is that LR shooting is all about barrels and bullets.

Shooting 20 round strings of fire with the intent of realizing zero dispersion makes the details of "consistent" paramount. Thinking about this, I remembered the phrase " angle of arc" relating to the need for consistency, so I did a Google search for more information about it. This search revealed to me why shooter consistency is important to good shooting--the consequence of inconsisteny is angular error which increases with distance.

Looking at the angle of arc picture I think illustrates to shooters who are not really thinking much about their relationship between the gun and the ground that more thought on perfecting the consistency of the position will have bigger benefits than will the pondering of things like bullets and barrels.

 

[40xs]

Probably a perfect example of this is in a heavy bullet in a revolver with a max. load. Some revolvers don't have enough movement on the rear sight to lower it enough to allow for the "whip" of the barrel, so to remedy this a higher front sight is necessary to establish a proper point of impact. it lowers the barrel, and point of aim to compensate for the horrific recoil.

 

[40xs]

I forgot to mention in the previous note that along the lines of what Sterling is saying, when shooting a very heavy kicking handgun it is MUCH, MUCH more important to maintain the very same grip and tension on the weapon each and every time to release the shot due to the extremes of shock and movement of the weapon. In ratio of recoil to the weight of the gun few people can consistantly group their shots out of a seriously recoiling handgun. they may be good with smaller calibers, but the .454's and .500's, etc. are different animals altogether. The same is true to some lesser degree with precision rifelry.

 

[Sterling Shooter]

I forgot to mention in the previous note that along the lines of what Sterling is saying, when shooting a very heavy kicking handgun it is MUCH, MUCH more important to maintain the very same grip and tension on the weapon each and every time to release the shot due to the extremes of shock and movement of the weapon. In ratio of recoil to the weight of the gun few people can consistantly group their shots out of a seriously recoiling handgun. they may be good with smaller calibers, but the .454's and .500's, etc. are different animals altogether. The same is true to some lesser degree with precision rifelry.

When folks tell me they're getting into Long Range and are looking for a good .300 Winchester Magnum, I suggest to them that it's a difficult caliber to control shot after shot. I tell them that, starting out, they might be better off with a .308. They are not interested in what I have to say. They've already made up their minds based on what they've been told by internet masters who have never participated in a Long Range event. At any rate, angle of arc is indeed about control. I'm thinking it shows clearly why bullets do not always go where aimed.

 

[Mr Flannel]

So, is controlling 'angle of arc' more a product of correct recoil management, or rifle design (caliber, barrel weight, stock weighting/balance etc.)? Which are we concentrating on here? I'm still a bit hazy on the concept, so as Graham said - a bit more concept definition might be in order, so some of us (i.e. me) can get a lock on it.

I'm intrigued by Brian Litz's claim that muzzle velocity can be impacted by hold and would really like to know how that is supposed to occur.

 

[Topstrap]

I have to do a bit of load development when weather co-operates in the next couple of days and will play a bit with what Litz was saying. Not sure what variation to expect with different things behind the stock and wonder if my cheaper chrono will be able to notice a difference.

Kinda wonder if a over simplified version of what he's saying is you see a runner getting into position, his kick off foot is against a hard angled brace so he can get maximum force pushing off, be a big difference if he was pushing against a bag of cotton balls. Or bouncing a ball off a hard surface compared to a soft surface. The results in a gun may be very slight but can see where having a hard hold and a light hold can possibly create a slight velocity difference, wonder if it's enough to cause an effect greater than what we get in variances in our reloading practices.

Have always said that our handgun accuracy is really dependent on grip, just never thought about any velocity change but more of a variance in elevation due to differences in grip or tension differences in fingers, wrist, elbow and so on from shot to shot that causes the barrel to be at very slightly different angles when the bullet exits the barrel measured in thousandths or tens of thousandths.

Think better equipment design to have less angle of arc or movement which helps hide variances in technique that varies slightly shot to shot is what we strive for to increase accuracy.

Topstrap

 

[Win_94]

I've been testing the "'angle of arc'" theory long before I heard the term "'angle of arc'".

I've done all sorts of tests to see if I could get a noticeable POI shift and the only way I found a shift was when I wired a firearm to a bench.
http://www.youtube.com/watch?v=JcR1meidxaI
When it is wired down the gun is held firmly, the other times the gun was held as lightly as I could.

An engineer that worked on the m198 Howitzer said,

At initial ignition of the charge, there is a small and barely perceptible motion of the barrel/breach. (only detectable by sensitive instrumentation) However, this motion is of so little significance that it has no practical effect on POI.

However, the motion widely accepted as recoil, were it to take place while the projectile were still in the barrel, would make POI so unpredictable as to make any sighting system useless; nothing more than decoration on the weapon.

If I hold the pistol lightly, then hold it firmly, the poi height doesn't change.
http://www.youtube.com/watch?v=SYDJETcN1rg

I tried with my Winchester with free recoil, vs a solid brace behind. I had to hold the rifle as light as I could with my trigger hand while having no cheek wield, which caused some inaccuracy, but the POI heights were basically the same.
http://www.youtube.com/watch?v=KyCLCL-1Hg8

I've talked to a Physicist and he concluded,

If you start out with a level barrel, the recoil will make the barrel tilt up by some angle when the bullet leaves the barrel. That angle is a constant times the mass of the bullet. The constant depends on geometry and mass distribution of the gun, but not on muzzle velocity, and not how long the bullet is in the gun.

The discussion was a bit different than "angle of arc" but the physics still apply. He was in total agreement with the engineer.

 

[Sterling Shooter]

Here's what we know for sure: if any aspect of contact between shooter, rifle, and ground is altered between shots recoil resistance will be different; and, the bullet will not go where aimed.

 

[Topstrap]

Win_94, I will agree that your testing might have not shown an increase in elevation change with your revolver at close distances but we've been experimenting with my Freedom 44 at 500 yards and it does have a significant elevation change at those distances with varying light and hard type holds. I think the movement is very slight and very hard to measure when testing up close but that compounds and is very noticeable when extending it out. I think it'd take a lot longer distances for those differences to show up when testing a rifle due to less movement with its design and more weight.

I was just talking to a buddy that was one of the best long range revolver shooters around about this same thing just the other day. Another knowledgeable long range shooter (J.D. Jones) will be at Blackies range possibly this weekend so we'll see if we all can get some definite data on this from two very qualified shooters that are experienced with this.

I'll plan for that next trip out to Rayners and take my Freedom and video cameras and try to get video of the gun and also on the target area at the 500 yard line. Very interesting stuff and has lots of opinions and results. What is being discussed in most circumstances is so slight it's overshadowed by all the other factors involved in making a good shot but is something that might separate the very top shooters.

Topstrap

 

[Sterling Shooter]

Even miniscule movement, for example an elbow a fraction of an inch out of place from one shot to another, will make it certain the bullet will not go in the hole vacated by its predecessor. Think about it, unless recoil resistance is identical from shot to shot, the angle of arc created between the line of bore at rest and the line of bore at bullet exit will be not be equal for the shots fired. Angle of arc is the thing we are attempting to make consistent. When we say the shooter must be consistent we are saying the outcome must be a consistent angle of arc. Since the elbow out of place would not be deemed important by some shooters, these shooters will never get to the highest plateaus of good shooting. Their inconsistent position error will likely be associated with ammunition consistency when shooting at short distance. Also, video of the sort we see here, does not serve to indicate the angle of arc effect. For example, although we know a sight adjustment of about 1/4 inch on a receiver sight can not likely be noticed by looking at the sight we nevertheless understand the effect. In addition, attempting to look at movement from recoil is looking at movement after the bullet has cleared the barrel and does not relate too much to this discussion. It's the movement of the bore while the bullet is still in the bore which is important; yet, with a shooter controlling the rifle, this movement is so relatively slow and miniscule as to not be apparent to the eye.

 

[Sterling Shooter]

So, is controlling 'angle of arc' more a product of correct recoil management, or rifle design (caliber, barrel weight, stock weighting/balance etc.)? Which are we concentrating on here? I'm still a bit hazy on the concept, so as Graham said - a bit more concept definition might be in order, so some of us (i.e. me) can get a lock on it.

I'm intrigued by Brian Litz's claim that muzzle velocity can be impacted by hold and would really like to know how that is supposed to occur.

Of course, the rifle design, as well as its weight will either enhance or detract from angle of arc being the same or different between shots. The newer designs out there like the Tubb 2000 or Barrett B98 seem to me to be designs which would help a shooter realize zero dispersion if the shooter was going for zero dispersion. I mention "going for zero dispersion" since the shooter must be cognizant of his relationship with the gun and the ground being identical shot to shot to have any hope of shots going through the same hole as preceding shots. All actions must be perfect. Since the shooter is not in control of all actions zero dispersion is an elusive goal.

 

[40xs]

In an attempt to offer an over simplified answer to Mr. Flannel's question regarding brian Litz's comment on velocity verses hold; Imagine a cartridge thrown in a fire pit. where is the most danger from? the lead slug or the flying brass? Chances are the slug will be lying close to where it was dropped. the brass will be hard to find. Same is similar to a limp wrist or weak hand hold on a semi auto pistol. some actions will not operate unless you have an adequate grip on the weapon. What would happen if you placed a large caliber "elephant" gun on a table and just tied a string to the trigger and fired it. The gun might fall off the table under recoil, absorbing some of the energy. Would this not affect the velocity of the projectile?????

 

[Sterling Shooter]

In an attempt to offer an over simplified answer to Mr. Flannel's question regarding brian Litz's comment on velocity verses hold; Imagine a cartridge thrown in a fire pit. where is the most danger from? the lead slug or the flying brass? Chances are the slug will be lying close to where it was dropped. the brass will be hard to find. Same is similar to a limp wrist or weak hand hold on a semi auto pistol. some actions will not operate unless you have an adequate grip on the weapon. What would happen if you placed a large caliber "elephant" gun on a table and just tied a string to the trigger and fired it. The gun might fall off the table under recoil, absorbing some of the energy. Would this not affect the velocity of the projectile?????

I wonder if, in your example, the bullet would actually push the rifle forward while in the barrel, like a cleaning brush would, when pushed through the bore of an unsupported rifle. I'm sure some internal ballistics expert has covered the topic; but, on this matter, it appears the "angle of arc" description I had remembered from long ago has never caught on as a way of indicating or revealing the need for exacting position consistency for ultra precision shooting.

 

[doc76251]

Interesting discussion. With several different topics that all aid and affect the repeatability of precision shooting.

Angle of arc (not a telling description of what were talking about but lets use it anyway) in this discussion appears to mean the movement of the rifle during the recoil and follow up phase. In a slung rifle the recoil will describe an arc or at least an oval during the complete cycle. In a prone gun (front supported by some means and driven from the rear) the rifle describes more of a "spike" than an arc. The slung rifle is being held under tension at one point (the elbow via the sling) and the pivot point being the shoulder. In a prone gun the rifle is not under any lateral tension but is "resting" on the ground/rest/bipod whatever, and the pivot point remains the shoulder. The slung rifle will move in the arc or oval because the sling/muscle tension/body position etc. is forcing the rifle back to where it started from. The prone rifle has no "return to battery" excepting the rear control of the firing and support hands/bag etc. The front end pretty much does what it will based on those influences, barring a directional muzzle brake or a really bad position it will recoil pretty much straight up due to the pivot point in the shoulder and how rifles are designed.

We already know that vibration is transmitted up and down the length of the barrel 6 - 10 times before the boolet ever leaves. Hence the concept of OBT and you can do the math yourself but there are a but ton of decimal places there. One could also correctly AssUme that the gun is moving before the boolet leaves but in most instances this is mitigated almost completely by the mass of the rifle until the boolet is gone. Again you do the math it's out there.

OK, so what! The gun moves. We got that.

The real question is

Can velocity (velocity is a product of pressure in this instance) be affected by hold? or position? or tension?

The short answer is yes. Variations in your shooting position will affect how the rifle recoils or affect it's "Angle of Arc". But I just said the angle of arc occurs after the boolet leaves so there should be no impact on accuracy. The variation in velocity will come when the tension used to hold the gun still is changed. If the rifle in the course of it's recoil can move more in one position or the other, the position with more movement will produce less velocity. Why? Think about it.

Movement requires energy. Any energy used to make the gun move rearward is less energy available to make the boolet go forward.

Wanna test it?

Set up your chrono and take your normal position and get a reading. Now really crawl into the gun HARD or put it in an unmovable vice, get a reading. Now squeeze just the trigger against the trigger guard (have somebody catch the rifle) and take a reading. Your normal position will net you what you are used to. The vice will give you a little higher velocity. The free recoil will surprise you.

That is why a consistent position, or stock tension or hold or grip or whatever is so important to consistent accuracy.

FWIW, YRMV etc. etc.

Cheers,

Doc

 

[Sterling Shooter]

While the bullet is in the barrel, is there not some rifle movement which will produce an angle from line of bore at rest and line of bore at bullet exit? And, therefore, would not an arc be produced too?

 

[40xs]

Sorry guys!! As it looks like I'm resurecting a dead thread! Responding to Sterling's last post, and coming from an old "pistolero", the answer is YES, it will to some degree and the level of degree is dependent on the consistency of the hold. To exemplify this, most seasoned pistol shooters know that light, fast bullets exit a barrel fast enough to print lower on a target ( with the same sight setting )than heavier and slower bullets will. it's time in the barrel lifting the gun in an upward arc. remember my earlier post on this where I mentioned that I had to modify my factory sights on a Ruger Blackhawk in order to zero the gun using very heavy and stout loads. They were printing way higher than the factory sights would allow me to lower. So I had to modify my sights to get the rear one lower on the frame. I was not strong enough to " hold" the gun down; too much energy generated. consistency, consistency, consistency. Anything less and you are opening up your groups! pistols, rifles, whatever, same principle.

 

[hlee]

Look at these three rifles closely...

Note the axis of the bore relative to the position of the butt stock. Note the height of the sights relative to the height of the butt stock. One of the things that is generally said about mounting a scope (at least on a hunting rifle) is mount it as close to the barrel as possible. But, in order to have the sights as close to the barrel as possible (like the Kentucky rifle) the drop at heel is severe in order for the shooter to be able to mount his/her head on the firearm. The result of this is that the shape of the rifle has a bend in it (the garand also has a bend but it is less severe). When the rifle recoils, the bend in the gun forces the rifle up. The same thing occurs with pistols. The AR-15 almost completely mitigates this as the drop at heel is effectively 0. Because there is no bend in the rifle (the shooter is directly behind the bore as opposed to below it), the recoil drives the rifle directly back. Modern adjustable stocks can be purchased with adjustable drop at heel butt plates. The downside to this is that the sights must be well above the axis of the bore in order to accommodate the shooter's head.

Q. Why is it so hard to get proper cheek weld on a modern rifle stock?
A. Modern rifle stock design has not yet caught up to the modern rifle sight (scope)

I believe the AR15 style of guns (including the "tube gun") are inherently more shooter friendly as the design more efficiently deals with the "angle of arc" problem that Sterling Shooter has defined.

 

[Sterling Shooter]

I think the design of the AR makes consistent shot to shot control more of a possibility than when using a traditionally stocked rifle. My own experiments, with emphasis on rebuilding the position identically shot to shot, suggests an amazing improvement in grouping when recoil resistance is controlled enough to produce similar shot to shot angle/arc between line of bore at rest and line of bore at bullet exit. I believe that in ideal conditions and using concentric ammunition with a very low es and sd a shooter capable of perfecting his position shot to shot could indeed realize close to zero dispersion. I also think that pursuit of rebuilding the position as identically as possible is the way to excellence once the fundamentals are grasped.

 

[Topstrap]

This has been an interesting thread and one I've posted in a couple of times. Nearly all guns will have movement of some type when fired. Correct positioning of the body and learning to hold the gun exactly the same time for every shot leads to shot duplication every time. Stock designs, heavier weights of the gun, muzzle brakes are a few things that mechanically we can alter to help us but the shooter still has to learn to do each shot the same each time.

Being a long time pistol shooter and still using modified versions of them for the 1000 yard matches has helped us learn how critical the human factor is for getting the best accuracy out of any particular weapon. We deal with a larger angle of arc than nearly any rifle and I've come to think of the "angle of arc" more of an "angle/arc to allow error".

Most new shooters have bad habits or poor mechanics when positioning themselves and their gun for the shot. That short time between the time the trigger is squeezed and the bullet exits the barrel and how the shooter/gun reacts each time has a lot to do with group sizes. A master class shooter can shoot nearly any gun, even heavy recoiling rounds very well due to doing everything right each time. An inexperienced shooter can still struggle even when shooting a heavy custom tack driver due to his inexperience. ]

You can buy the very best equipment and move up the score sheet and bypass some of the learning curve with equipment but you will finally hit a plateau and then they have to learn proper technique. I've seen a couple other pistol shooters add comments to this thread and we've found nearly the same thing. A good precision pistol shooter finds switching over to LR precision rifles a lot easier than the other way around. Nothing beats quality range time with a good teacher and learning something from each round that goes downrange.

Excellent thread, was not sure of some of the terms used to describe techniques in some of the posts but if you pay attention to details that is where the top shooters will pick up those extra points or targets. When you start to feel the pressure of each finger touching the stock or how much pressure your palm is applying against the grip, does that cheek weld feel the same, and does it all feel "just right"? Same as when a bowler turns around after releasing a ball with a big grin and saying it "just felt right" and it's a perfect strike. Same thing here and then you'll start to wonder why you never noticed it before.

Good luck,

Topstrap

 

[Sterling Shooter]

Topstrap and All,

Thanks for posting your views. As I mentioned earlier, I do not know where the phrase angle of arc originated, or if it indeed was used to describe the movement of the firearm as I believe it to mean. It does seem to communicate the nature of rifle movement while the bullet is traveling through the bore, as well as the need to control such movement consistently to realize the best results. Nevertheless, since the physics of the matter are not clear to me, I am somewhat uncomfortable about the use of the phrase in my instruction on properly building the position, even though the phrase seems to identify the reason why it is important to re-build a consistent shooter, gun, and ground relationship from shot to shot.

 

[Sterling Shooter]

Update,

This is something I discovered in a USAMU manual: "Muscular relaxation also permits the use of maximum bone support to create a minimum arc of movement and consistency in the resistance of recoil".

The implication is 2 fold, when muscles are relaxed, bone/artificial support can make the angle/arc between line of bore at rest and line of bore at bullet release more similar than dissimilar; and, when muscles are relaxed, bone/artificial support can maintain the position from shot to shot. Each implication is a gain of consistency for accuracy.

Is my understanding correct? Any ideas?

 

[40xs]

I'll buy that! Mainly due to the fact that muscles react involuntarily due to any shock created, so, the less muscle involved should aid in consistency.

 

[Lowlight]

Recoil management is a key component, especially with tactical shooters, we are doing more and more in the recoil management arena so that we have consistency from shot to shot.

Problem is, much of the training out there, especially prior to the last few years was based on Sling Shooting doctrine even though you are using a support. Take F Class for example, their rests are designed to enhance consistency from shot to shot so you are not gonna see the variations a Palma Shooter with a sling will experience. Apples and Oranges.

Tactical Shooters are multi positional, so we have developed techniques to combat recoil variations, and use recoil management effectively. Video shows we clearly are keeping the rifle on target so the individual can see the results of his shot. Even when off the ground. Back to previous doctrine, Spotter / Shooter relationship, it was the task of the spotter to manage the shot after it left the barrel. The shooter was the junior man, basically just a monkey pulling the trigger. No longer, we are empowering the shooter to control everything from bullet shot to target. By managing recoil, getting the shoulders in front of the hips, and seeing the shot results downrange, the shooter can adjust and follow up much quicker than ever before. Many time on the line, even with a spotter, before the spotter as uttered his first word, the shooter is replying, "Got it" and sending another round hitting the target. That is far cry from lessons taught in the past. It's why we focus on eliminating angles in the shooters position, and squaring up. Even standing we square the shoulders to the target, lean into it, and can manage the shot after the bullet has left the barrel.

I too highly doubt the 20-30fps deviation, heck depending on the chronograph he used to test that, variations in the placement of the bullet past the screens can cause that error. Not the recoil differences of the rifle. As [MENTION=825]TiroFijo[/MENTION] noted, 8.5fps is a known number, that 3x increase seems to be pattern people are noting of lately. Those not caught up in the US Ballistic Politics of the Day, constantly email about the increases stated in a lot of variables /effects. I am not gonna elaborate, but many outside the US don't agree, and some quietly inside the US too. Adding 3x the value is becoming more, more evident of late. I will say, my PVM-21 needs to have the shots break perfectly in the same spot or it will easily demonstrate that variation. I retired the unit because of it, but prior I had to draw a line for my reticle in order to index the shot. Skyscreens style chronographs with something a simple as partially cloudy skies can cause variations. If you are demonstrations a free recoil method vs a hard hold, you can easily send the shoot at an odd angle through the screens, cause a unit error.

Videos make it easy to demonstrate, the rifles barely moves when proper recoil management is employed. A Sling shooter can definitely use the method or the idea of it to fine tune their position and use the variation to show inconsistency from shot to shoot. But a support shooter... If they learn anything about recoil management should not see this variations in where the bullet is release. That is the main problem with teaching doctrine designed for a difference discipline.

 

[Sterling Shooter]

I'll buy that! Mainly due to the fact that muscles react involuntarily due to any shock created, so, the less muscle involved should aid in consistency.

Do you think my interpretation, or what I believe the statement to mean is correct?

 

[M40_A1]

I've talked to a Physicist and he concluded,
"If you start out with a level barrel, the recoil will make the barrel tilt up by some angle when the bullet leaves the barrel. That angle is a constant times the mass of the bullet. The constant depends on geometry and mass distribution of the gun, but not on muzzle velocity, and not how long the bullet is in the gun."

...most seasoned pistol shooters know that light, fast bullets exit a barrel fast enough to print lower on a target ( with the same sight setting )than heavier and slower bullets will.

You may not be a physicist, 40xs, but I suspect you stayed at a Holiday Inn the night of May 21st!