Practical limit to group size wonderment

[ATLDave]

Benchrest shooting (a discipline which I have never participated in) is interesting because it produces some interesting knowledge and technical experimentation.

None of us here are likely to be astronauts, but we've all benefited from the scientific and technical discoveries first made in the context of aerospace work. The car you drive to work or the grocery store probably isn't a formula one race car, but there's a good chance that some of the technical innovations from racing are in that car.

 

[ATLDave]

machines don't judge the wind very well.

Interestingly, we're rapidly approaching the point where machines can judge wind better than any human possible could. See, e.g., http://www.accurateshooter.com/optics/new-wind-reading-lidar-laserscope/

And note that the limitation described in the last paragraph of this story isn't necessarily correct/present. Some laser-based wind-reading technologies are essentially summing the wind over the entire line of sight between the shooter and the target. Brian Litz has a really interesting chapter or two on this in one of his books on long-range shooting.

 

[Tirod]

Still, the point is that a firearm shot by a machine rest alone cannot do as well in variable cross winds. The human operator can and has for decades.

An additional machine correcting for windage still can't interpret the overall gusting pattern and make shots based on the human intuition and experience - IMHO. And we do see that with snipers in combat. However, with Tracking Point type optics correcting for what data it collects, the overall results will achieve a better result more quickly than the years necessary to develop the human skill. It's not that the human can't get to a level where they are effective, it's the Cost/Benefit Ratio that starts creeping in. The corrective scopes on the market will bring up a newer shooter to speed in weeks vs the years of practice a sniper put in and what it costs us to get him there.

Of course, it his computer controlled windage and elevation optical calculating machine goes on the fritz out in the field, said sniper still has to continue the mission, and he better be able to do it. This is where we see cost/benefits have their limit - take away the helping hand and it's all right back down to knowing and being able to do it. One parallel would be a mechanic reading the codes on a newer car - nope, sorry, the codes do NOT tell you what is broken. He still has to test and diagnose it. We haven't fired all the mechanics and put kids in the dealership who replace parts as the computer directs (despite claims by some.)

We aren't going to hire newbies to fire optically aided sniper rifles either. If anything pulling the trigger is just one small part of the overall skill set. That two pound optical device isn't welcome unless it's capable of doing something the shooter can't.

 

[ATLDave]

Have you read any of Brian Litz's books that are based on WEZ analysis? It's one thing to be good at reading wind, it's another to read it +/- 1mph over, say, 1,000 yards. In anything but ideal conditions, there's just no way humans can reliably read wind with that level of precision.

FWIW, I'm not advocating the use of such devices in any particular application or at all. I'm just pointing out that it is incorrect that machines cannot read wind as well as humans. There are devices either currently available or on the cusp of availability that read wind with a level of precision that literally cannot be matched by humans looking at tree branches waving. Just as laser rangefinders offer a level of precision that simply cannot be matched by humans eyeballing things or even using stadia lines or mil-dotting.

 

[Bart B.]

Regarding the wind; some facts.....

Crosswinds in the first third of target range have a much greater effect on bullet impact at the target than the same wind in the last third of target range.

Winds above the line of sight are faster than this in the line of sight.

 

[lysanderxiii]

It seems to me the real practical limit to group size is the caliber of the bullet . . .

 

[murf]

bart b.,

i hear that "doping the wind" is an art form. one that i have not come close to perfecting. i was commenting on bikemutt's post #20 as an answer to how a human can beat a machine. a human still has to set up the machine, set up the rifle and correctly cycle the ammo. there are still a lot of common variables that the human can place in its favor to beat the machine.

murf

 

[murf]

atldave,

machines read the wind much better than humans ever could. machines can't judge the wind, however. tirod, apparently, is an excellent wind judge. bart b., according to his tag lines, is also an excellent judge. thx for the "dope" on judging the wind.

thx for the info on the latest wind technology, atldave.

murf

 

[PapaG]

I visited the Sierra plant a few years back. Convinced the VP to give me on off-hours tour. What a nice guy. Downstairs, he showed me the test area complete with machine rests, aluminum blocks with barreled actions installed, and the underground range. He took me over to a scope focused downgrade and asked "what do you think?". I told him that was a great group at 100 yards. Big grin, lots of teeth, "that's 300 meters".
Fabulous loading room adjacent with Rockchuckers, Dillons, and others.
What I learned was that uniformity and repeatability are key to accuracy, and I've sent my share of projectiles downgrade.
BTW, that underground tunnel goes under the interstate north of the plant.

 

[murf]

lysanderxiii,

and i thought it was the caliber of the shooter.

murf

 

[Orcon]

Interestingly, we're rapidly approaching the point where machines can judge wind better than any human possible could. See, e.g., http://www.accurateshooter.com/optics/new-wind-reading-lidar-laserscope/

In my world, the field of process engineering, it's been said that a system isn't truly broken until it has a sufficient number of features. Sometimes more is less.

 

[Bart B.]

Reading the wind is not an art form. Art makes people feel good. Reading the wind is observation skills and simple math with knowledge of your ammo wind drift facts that makes you shoot good. It's looking through a scope focused 2/3rds the way to the target so the heat waves (mirage) can be seen wrinkling across the path bullets take. A skill is needed to estimate the speed the mirage moves and how much windage correction is needed for the ammo and range.

At wind speeds 5 mph and slower, corrections of 1/2 or 1/4 MOA can be discerned then applied to the sight. As wind speed changes in such a condition, windage spread of a shot group can be held to 1.5 MOA at 1000 yards. Some people will detect a stable wind then shoot several shots 7 to 8 seconds apart all well entered on the bullseye. David Tubb sometimes shot rapid fire that way in slow fire 1000 yard matches keeping all shots in the 1 MOA X ring.

 

[Offfhand]

Reading the wind is not an art form. Art makes people feel good. Reading the wind is observation skills and simple math with knowledge of your ammo wind drift facts that makes you shoot good. It's looking through a scope focused 2/3rds the way to the target so the heat waves (mirage) can be seen wrinkling across the path bullets take. A skill is needed to estimate the speed the mirage moves and how much windage correction is needed for the ammo and range.

At wind speeds 5 mph and slower, corrections of 1/2 or 1/4 MOA can be discerned then applied to the sight. As wind speed changes in such a condition, windage spread of a shot group can be held to 1.5 MOA at 1000 yards. Some people will detect a stable wind then shoot several shots 7 to 8 seconds apart all well entered on the bullseye. David Tubb sometimes shot rapid fire that way in slow fire 1000 yard matches keeping all shots in the 1 MOA X ring.

When trying to outrun changing wind conditions a slow pit crew can be a vexation. But fast pit service can be a blessing, as it was many years ago when I had the good luck to have shooting pal Bob Jensen in the pits. He knew I was going after the 600 yard record and gave me tremendous service. Some Benchrest shooters practice what is known as "running" when they catch a momentarily stable condition and get off five shots on the record target in about 20 seconds, and even ten shots in a half minute or so with a fast loading rail gun. Attached is a photo of one of my bench rifles with a RBLPRE action (Right bolt, left loading port, right eject.) which speeds up rate of fire.

 

[Jason_W]

To each their own, but I always find punching paper from a bench to get tedious in a hurry. Blowing up old fruits and veggies with offhand shots is way more fun than trying to print tiny groups. But that's just me. I get bored pretty quick.

 

[Bart B.]

I bunked with Bob Jensen when the USA team was in South Africa. Known him since the '60's. Shot team matches with him.

I, too, had great pit service when I'd put 12 shots from a Garand in the 6" X ring at 600 in an Interservice rifle match at Quantico MCB. Included two 3-shot rapid fire single round loaded strings in weird wind conditions. Then I fired the 13th shot with a perfect call . . . . one target to the right. Finished with a 190-15X. 17 X's counting that crossfire.

Good barrels properly fit to receivers will shoot half MOA at longer ranges over 40 to 50 shots fired every 10 seconds. Aiming them to do twice that is something else.

 

[Jim Watson]

Will electronic targets taking the pit crew and target service times out of the picture improve scores by letting the shooter hammer the target when conditions look stable for a short while?

 

[Offfhand]

To each their own, but I always find punching paper from a bench to get tedious in a hurry. Blowing up old fruits and veggies with offhand shots is way more fun than trying to print tiny groups. But that's just me. I get bored pretty quick.

It doesn't get tedious at all when you are shooting in a National or World Championship and competing against some of the finest riflemen on the planet. Give it a try, you won't be bored, you'll probably be terrified.

 

[Howard Roark]

It's looking through a scope focused 2/3rds the way to the target so the heat waves (mirage) can be seen wrinkling across the path bullets take. A skill is needed to estimate the speed the mirage moves and how much windage correction is needed for the ammo and range.

What about when the wind is blowing hard enough for the mirage to flatten out and become unreadable? Is this even possible and if it is are there any other indicators of wind speed and direction that the shooter can rely on?

Will electronic targets taking the pit crew and target service times out of the picture improve scores by letting the shooter hammer the target when conditions look stable for a short while?

Yes, for shooters that are capable of taking advantage of it, it is already happening. F Class especially benefits from this since in many aspects it has evolved into bench rest from the prone position.

Eliminating the physical need to pull targets is absolutely a benefit of electronic targets. Everybody gets the same service no matter their pullers physical condition or aptitude. No more calls to speed up service on target number "_".

 

[lysanderxiii]

I am going to go out on a limb and say the practical limit is .1 MRAD, at all ranges.

For a production gun.

With production ammunition.

 

[Bart B.]

When the wind is blowing hard enough for the mirage to flatten out and become unreadable, guess from experience, or use a wind gauge to get, wind speed, then multiply that by range in hundreds of yards, then divide by the target range wind constant for the bullet at its muzzle velocity, then multiply by the approximate sine of the wind angle.

Example, 30 caliber 175 grain match bullet leaving 2700 fps has a 1000 yard wind constant of 12. So with a 25 mph wind times 10 hundred yards equals 250; divided by 12 equals 21 in round numbers. For a 9 o'clock full value wind, the correction's 21 MOA. For a 8 or 10 o'clock wind, it's .9 times 21 or 18 MOA correction (some use 7/8ths value, others a 3/4 value). If wind's at 7 or 11 o'clock, it's half value 'cause the cosine of 60 degrees is .5.

At 300 yards, the wind constant for the same load's 15.

This happened in a team match and no mirage was visible, so the coach told me to start at 28 minutes left, I fired and the spotter came up a 9 just off the 10-ring at 9.

You can make your own wind tables with constants for each load at all ranges using ballistic software.

 

[Walkalong]

A tight group from a benchrest tells what a rifle can do only when it's fired in totally free recoil.
If held by someone, their human variables open up its groups a lot; sometimes 2 MOA or more.

I'm going to disagree with you Bart, as I, and some others, handled the stock (Never got used to shooting free recoil), and it didn't result in any 2 MOA and bigger groups. It is tougher to do, but only by a bit. Or where you talking about at 1000 yards? Maybe then. Dunno.

Target shooting is by no means a joke. It's not for everyone, and that's OK, but to call it a joke is narrow minded.

Because it is so difficult to do, shooting a group like this is extremely satisfying. Just like hunting a difficult game animal and finally bagging it.

If it was easy, everyone could do it, and there would be no satisfaction in accomplishing it. Like the quote from A League of Their Own, the hard is what makes it great.

But yea, you don't need a 1/4 MOA rifle for hunting unless your one of these people who like to shoot at really long distance, and then a very accurate rifle would be handy.

 

[Slamfire]

Will electronic targets taking the pit crew and target service times out of the picture improve scores by letting the shooter hammer the target when conditions look stable for a short while?

It may very well change the game from where winners are determined by their ability to judge range wind conditions, to who is lucky and has a very accurate rifle. Last F Class match I shot at CMP Talladega, shooters near me finished their 20 shot for record strings in 2 minutes 19 secs. I believe these guys had a viable strategy, use the sighting period to get in the 10 ring, then, during record period, if they are in the 10/X ring, go "full auto" before the wind changes. With the rifle on a rest and sandbags, the faster shooters will be able to load, shoot, observe the shot, in less than 7 seconds per round.

Norway has a shooting game called "stangskyting. Each shooter shoots two series of as many shots he can within 25 seconds, at two unknown ranges. the first is somewhere between 125 and 175m, and the second (1/4 figure) is between 200 and 250m.https://en.wikipedia.org/wiki/Stangskyting http://bulletin.accurateshooter.com/2009/12/more-interesting-shooting-competitions-from-norway/

 

[Howard Roark]

Example, 30 caliber 175 grain match bullet leaving 2700 fps has a 1000 yard wind constant of 12. So with a 25 mph wind times 10 hundred yards equals 250; divided by 12 equals 21 in round numbers. For a 9 o'clock full value wind, the correction's 21 MOA. For a 8 or 10 o'clock wind, it's .9 times 21 or 18 MOA correction (some use 7/8ths value, others a 3/4 value). If wind's at 7 or 11 o'clock, it's half value 'cause the cosine of 60 degrees is about .9.

Ah yes, the good old USMC sight adjustment method. There are plenty of charts out there with this information already calculated for given calibers and distances like this one: http://mgray.hopto.org/shooting/TgtReplicas/WindChart-762.JPG

Is there any advantage or disadvantage to using holdover as opposed to adjusting the sight or scope for corrections for wind conditions?

 

[Bart B.]

I've aimed 30 caliber magnums dead center on the target to my left to shoot 10's and X's on my own. That's an 9.6 MOA hold over.

Holding off with a scope is often done in team matches. You don't have to leave position to adjust the sight. If the rifle scope is focused a bit short of target range, the mirage can be read and holdovers used as needed to correct for wind changes without leaving position to use your spotting scope.

Canting the rifle so the spirit level on the front sight can be done to adjust windage a minute or two. Easy to calculate where the bubble needs to be for 1 MOA windage change at range after the front sight is level with the rear sight windage arm.

 

[Bart B.]

I'm going to disagree with you Bart, as I, and some others, handled the stock (Never got used to shooting free recoil), and it didn't result in any 2 MOA and bigger groups. It is tougher to do, but only by a bit. Or where you talking about at 1000 yards? Maybe then. Dunno.

I know some stool shooters gently hold benchrest pin drivers. Pin heads are smaller than tack heads. Some do that as its easier in changing winds; evidenced by unlimited class rail guns having bigger aggregate record numbers than other stocked classes. Those rifles have much less recoil than a 9 pound 300 Win Mag; much lighter triggers, too, they're not bumped with a 3 pound force every shot.

My 2" remark refers to benchrest shooters shouldering the rifle hunkering down on it as it rests atop bags. I've watched people shoot rifles that bad at 100 yards when the rifle and its ammo shoots inside half an inch all day long fired prone in an F class open position by its owner.