Range and Wind Uncertainty in Field Target

 

From observing and talking to top shooters it is evident to me that on the non-discipline shots ranging and wind reading are the two most important factors in consistently hitting a KZ.   But how much does the ability to range accurately and read the wind increase the chances of a hit?  Is there a way to quantify range and wind uncertainty?

Bryan Litz has written several books about accuracy and precision in long range shooting.  

He takes a very methodical approach and isolates factors that impact accuracy and precision.  In light of those factors, his writing and consulting assists shooters in making intelligent choices about where to spend money on equipment and their practice time.  His books are well written and worth a read.

Having read his books, I became interested in what he calls his Weapons Employment Zone (“WEZ”) analysis found in his Applied Ballistics analytics software.  I was curious of his software could model range, wind, and other uncertainty effects with airguns to evaluate the impact of  ranging and wind estimation errors on hit percentages.  After some communications with Applied Ballistics, it was confirmed to me that the software could model at our field target ranges.

While this is not a review of the software, I think it is worth mentioning a few things out of the gate about it.

  • This is a PC program and the user interface is not very slick.   The focus is clearly on function.
  • It only uses the G1 and G7 drag models.  
  • There is a bullet database with custom drag curves, but this is not helpful for us airgun shooters since there are no pellets in the database. I selected the G1 model in the software.
  • As a tool for making range cards, it does not allow the user to get results in clicks.
  • It is not a product designed around the specific needs of air rifle shooters.

With that out the way, my primary aim was to get statistical results so that I could compare trends based on basic inputs about the ballistics of pellets.

As an initial foray into this, I decided to limit the analysis to two commonly used pellets:  the JSB 10.3 and the JSB 7.9.   While there are other pellets in common currency in FT, the purpose of this initial analysis is to find trends in the data and draw some general conclusions at 20fpe and 12fpe power levels.

I am certain that upon careful inspection and thought that the technical-minded in our FT community can raise questions about the approach and results.   To that end, any and all critiques are welcome. However, all I am doing is using the Applied Ballistics Analytics software to get the results.  So the critique will either be on the variables I used or the operation of the software.  I can only defend my choice of variables, so let us start with the basic ballistics variables I used:

  • JSB 7.9g
    • BC .021 (Chairgun)
    • Diameter .177″
    • Length: .216″
    • FPS: 822 (11.9fpe) with SD of 5
  • JSB 10.3g
    • BC .031 (Chairgun)
    • Diameter .177″
    • Length: .246″
    • FPS: 932 (19.9fpe) with SD of 5
  • Wind 7mph at 9 o’clock to shooter
  • Ranging SD +- 1, 2, 3, 4 and 5 meters
  • Wind speed SD +- 1, 2, 3, 4, and 5 mph
  • Rifle capable of 1 MOA extreme spread
  • Target distance is 50 yards
  • Target  is 1.5″ circle

I had initially considered modeling 45, 50 and 55 yards using the 1.5″ KZ.   However, after starting the process and looking at the results from 45 and 55 yards, I concluded that the 50 yard analysis was representative and instructive at least for the last ten yards that we shoot.  Granted, under our rules we have the largest kill zones out past 45, but that is also where the wind and ranging challenges are most difficult.

The results of multiple calculations at the 50 yard target with the 1.5″ KZ are in the table below.   The Y axis is the range estimation error in meters (the software, oddly, does not allow one to set this in yards) and the X axis is the wind estimation error in MPH.   The software calculates a hit percentage based on the ballistics of the projectile.     In my analysis I focused on the range and wind effects and the relationship between those effects on hit percentages.

 

Based on an informal poll of Tar Heel Air Gun Club members, most Open and WFTF shooters say they are able to range to within 1 to 3 yards of a 50 yard target.   Hunter shooters indicated they could range within 3 to 5 yards of a 50 yard target.

Example 1:

  • 20fpe rifle with JSB 10.3’s;
  • Range SD 1 meter at 50 yards;
  • Wind SD of  3 mph;
  • then the hit percentage is 75.49.

Example 2:

  • 12fpe rifle with JSB 7.9’s;
  • Range SD 1 meter at 50 yards;
  • Wind SD of  3 mph;
  • then hit percentage is 55.27.

Example 3:

  • Hunter piston at 12fpe
  • Range SD 4 meters at 50 yards;
  • Wind SD 2 MPH
  • then hit percentage is 35.44.

Example 4:

  • Hunter piston at 12fpe
  • Range SD 2;
  • Wind SD 1;
  • then hit percentage is 82.42.

The results assume a rifle/shooter combination capable of producing a 1 MOA group.   This is an incredibly huge assumption.  However, we are simply looking at the impact of range and wind uncertainty on the hit percentages applied to that (big) assumption to find trends in the data and see if any useful conclusions can be drawn.   Do not read the results to mean that any given shooter will  have the hit percentage shown in the tables.  Also implicit in the analysis is that the wind is constant.   We know that in the real world wind is often not constant in direction or speed.

Conclusions:

  • Range uncertainty results in vertical errors.   Wind uncertainty results (primarily) in horizontal errors. A shooter should seek to reduce those uncertainties because
    • A perfectly placed shot in the vertical axis has more room for horizontal error induced by wind uncertainty; and
    • A perfectly placed shot on the horizontal axis will allow more room for vertical error induced by range uncertainty.
  • The ballistics of a 10.3 JSB at 20fpe gives more room for error in ranging and wind estimation errors at every similar combination of wind and range SD’s than the JSB 7.9 pellet at 12fpe.
  • The drop off in hit percentages after 2 standard deviations for both wind and range is remarkable with the 7.9 grain pellet at 12fpe compared to the 10.3 grain pellet at 20fpe.
  • The major advances in hit percentages in Hunter division (shooting at 20fpe) will come from the ability of the shooter to range a 12x scope and use other ranging methods such as bracketing to reduce range uncertainty.
  • A Hunter division shooter must be adept at reading the wind to offset ranging errors inherent in the optics of parallax ranging a 12x scope.
  • Hunter piston shooters who shoot around 12fpe have the worst case scenario of range uncertainty and 12fpe ballistics.
  • Assuming the average WFTF and Open shooter can consistently range to within 1 or 2 yards on a 50 yard shot, hit percentages are increased with better wind reading.

 

Episode 13 – Interview with Harold Rushton (Part 1)

 

In Austria just before the Worlds in Germany.championships, and done very well on the international stage.   Harold has given back to the sport in helping other in the sport with his website at usfieldtarget.com and as an AAFTA governor.

 

Harold Rushton first came into the sport in 2006.

Since then he has won state and U.S. national championships, and done very well on the international stage.   Harold has given back to the sport in helping other in the sport with his website at usfieldtarget.com and as an AAFTA governor.

Hope you enjoy part 1 of this interview.

Greg and Harold were awarded the Masterclass patches in Portugal. Only about 15 shooters worldwide achieved this with a score 92.5% or better.

 

Episode 12 – Getting Started in WFTF (on a budget) with Tom Holland

Tom Holland has been shooting competitively since he was in high school.  He holds indoor national and world records with a crossbow.

Tom discovered field target in 2009 after visiting aimg9503111-1n airgun store on Long Island and was hooked.

He bought a Benjamin Marauder to get into field target and has since expanded his airgun collection to include a Steyr and RAW TM1000, but he has gone back to the Marauder as his main gun, placing second at the 2016 Pyramid Air Cup with it.

In this episode Tom talks about his development as a shooter and how eventually ended up in WFTF shooting his Marauder.   In talking about the gear and gu2011-03-13_15-31-38_425ns, we cover the basic WFTF rules.     We discuss getting into field target on a budget, how Tom has modified his Benjamin Marauder with a regulator from airgunexporter.com, scope choices, and advantages of a regulated air rifle.

Tom talks about the challenges of shooting a 12 foot-pound energy rifle, pellet selection,  the rules, and some basics of reading the wind.

Hope you enjoy the episode.

 

 

 

 

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Episode 11 – Introduction to Pistol Field Target

In this episode, Bob Dye talks about his history shooting 10 meter air pistol, how he discovered field target, and the bd-2history of pistol field target since 2012.   Bob covers the rules, open and hunter divisions, and selection of a pistol scope and other gear.

This episode is aimed at those new to field target who want to learn more aboutcz200s-pardini pistol field target and those of us who have shot rifle field target but may want to try pistol.

The pistol rules are in the AAFTA rules at www.aafta.org.

 

Episode 9 – 2016 AAFTA US Field Target Nationals Recap

The 2016 AAFTA Field Target National Championships are over and Chris and I are back in North Carolina.   We had a great time.   In this podcast (recorded on the road on our drive back) we talk about the match.  We enjoyed our time in Michigan shooting, seeing old friends, and meeting new ones.

Rifle results can be found here.  Pistol results are here.

Stay on past the closing music and hear some outtakes from the awards ceremony.

Episode 8 – David Slade

David Slade has been shooting airguns a long time and has enjoyed every minute of it.

He has been a part of the sport from its early days in England and brought his love for airguns and field target to the U.S. in the early 90’s.

ft-cover

David on the cover of Airgun World, May 1987

David has been on the AAFTA board of governors, he has been part of multiple clubs in the U.S. and in England and has made many friends along the way.

He has won a national championship, started Airgunwerks, and built a tremendous air gun collection.

Airguns and FT have allowed him to travel the world, meet the love of his life, and more.

We hope you enjoy this episode of the Field Target Podcast.

Airgunners of Arizona

Airgunners of Arizona will celebrate its 25th anniversary in 2017.

With over 30 members, this aoaAAFTA member club has a match each month and the club web site is the source of information about about the club, the history, and upcoming events.

In this episode Scott Allen interviews Mark Kauffman.

Review of the Rowan Engineering Digital Sidewheel

I like technology.  I tend to be an early adopter.  Sometimes that’s good and sometimes not so good.

Some months ago, when Rowan Engineering released its digital side wheel, I contacted Dave Rose, the owner. At the time hdsw-1ae was not ready to ship any to the US, wanting to continue to make certain that the side wheel is reliable.

I kept checking the Rowan site and with Dave and, eventually, he let me order one.   It was and may still be the only one in the US.  The Rowan web site, as of 9/22/16, says: “DSW is presently only available to UK customers. Will we be accepting overseas orders shortly.”

In any event, he accepted my order a few months ago but I had to wait a bit for the order to ship so he could make mounting brackets for my 34mm scope tube and they were also working out an issue with a bad batch of microchips.

This is a review after a couple of months of ownership.  By no means is this the end of the review, as I will be using it and waiting with interest for future software upgrades.

After having a chance to work with this device some I made a requst to the Board of Governors to ensure it is legal.  The concern I received back is that it had a wind indicator on it.  As discussed in the audio, it has no way to measure wind or wind direction, all you can do is tell it from which way you believe the wind is blowing.  The feature can be turned off in the parameters.  I discussed the issue with Dave Rose and he made a software update that removes the compass functionality entirely and requires that you put a country code in so that it must boot in a certain way and you get this from v1.06 of the software.

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So the visual boot up process should make it very easy for anyone to confirm the device is within the rules   The fact that this device  is run by software that the manufacturer is willing to update to ensure rules compliance will hopefully be reassuring to AAFTA as it considers this device and devices like it in the future

I need to get this out of the way: this is in no way a sponsored review. I paid full price for this piece of kit (as the English say). Rowan is not paying me.  (Which I might say is very unfortunate…. it would be great to defray the costs of doing the podcasts, but that’s okay, the lack of money from sponsors takes away concerns over biased reviews.)

Dave did throw in cool baseball cap (maybe they are called cricket caps in the UK?) with “Rowan Engineering” on it in white letters.  I figure that was meant to take some of the sting out of the delay.  Uber nice hat but it’s way too small for me, but the thought was most generous.  Maybe Chris Berry can use it.

Listen to the audio for details on installation, setup and use, and my impressions.

I hope you enjoy the audio review.

 

The photos here are courtesy of the Rowan website.   Here’s the link to the DSW page at Rowan.  The PDF manual is here and if you are seriously thinking about getting one of these, your should read it.

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