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Measuring Shot String

Discussion in 'Shooting Related Threads' started by phirel, Mar 15, 2009.

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  1. phirel

    phirel TS Member

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    I am in the preliminary stages of putting together a system of measuring shot string. I plan to shoot at a sheet of tin roofing and record the sound the shot string makes as it strikes the tin. By estimating the velocity of the shot at 40 yards, using tables, and measuring the length of the sound of the shot hitting the tin, the shot string can be easily determined. I need some advice on the best type of sound recorder to use (high speed?) and an accurate way to measure the length of the sound of the shot hitting the tin. Anyone have some suggestions for me?

    Pat Ireland
     
  2. wireguy

    wireguy TS Member

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    I have wondered if some kind of pressure recording board that could record the timing of the individual pellet strikes could do that. If the board would record the location of the different strikes a 3-D computer model of the shot string might be created. Yours is a lot more low tech and probably more feasable though Pat.
     
  3. JBrooks

    JBrooks TS Member

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    Pat,

    Make sure you stand with the recorder on the opposite side of the tin from the shooter!

    Congrats on the doubles wins.
     
  4. Paladin

    Paladin Well-Known Member

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    Get access to a high speed motion picture camera. High end stuff that TV networks use. I have seen footage of the shot string breaking a target in incredibly slow motion. Can't remember by whom though. Everything was visible, from the initial pellet impacts, to the very last trailing pellets.

    It would be very easy to record and measure a shot string over a graduated measure, at almost any distance you wish.
     
  5. John Browning

    John Browning TS Member

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    Pat, maybe a easier way would be to send in your request to Discovery Channels, Time Warp. I watched them film a shotgun shooting targets and balloons and it was very informative. John
     
  6. Neil Winston

    Neil Winston Well-Known Member

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    The trick won't be recording the sound, Pat, it will be determining the shot speed. Are there really any tables which give the speed of the pellets at the head and the tail of a shotstring?

    And if you knew that, wouldn't you know how long the shotstring was, pretty-much?

    Neil
     
  7. Paladin

    Paladin Well-Known Member

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    The speed of the pellets at the head of the string are easy enough to get with a light triggered chrono, but getting only the tail shot velocity would be very very expensive, I'm sure.
     
  8. RAScott

    RAScott Member

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    Seen a video of a shot string by welderman on this site, I believe pretty interesting, In slow motion toke a while to get it, but he did.
    Bob S
     
  9. Dednlost

    Dednlost Member

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    Wicked Neil, just plain wicked. LOL
     
  10. Frank C

    Frank C Well-Known Member

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    Pat, I believe that Welderman will be working on an improved video of the shot string this spring, when the weather warms in Mass. Good meeting you on Sat morning!!-Frank C
     
  11. dverna

    dverna Active Member

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    Does it matter?

    Unless there is a simple way to test different loads how do you work up an "optimum" load?

    It is bad enough that we should fire 10 shots just to evaluate a two dimensional pattern, Now this Ireland guy is screwing up my pea little brain by wondering if I have a "good" shot string.

    Damn you Pat. I know I should not have opened this thread,

    Don Verna
     
  12. overbored

    overbored Member

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    Pat We set up the scenario you are about to try. We had thousands of dollars worth of recording equiptment, and several shooters lined up for our testing. Every thing was going as planned until no one could hit the roof.(or the building) Good luck.

    overbored
     
  13. hmb

    hmb Well-Known Member

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    Seek psychiatric help before it is too late. HMB
     
  14. EuroJoe

    EuroJoe TS Supporters TS Supporters

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    "Shotgunning, The art& the science" by Bob Brister, shot strings were printed out on a long pattern sheet towed behind a vehicle.
     
  15. goatskin

    goatskin TS Member

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    The physics of the shot string are not hidden. In addition to Brister's ~Art & Science~ Brister and Jess Briley got a-hold of some work done at the Tula Arsenal when TA developed their 5-diameter international skeet choke. Tula used a rotating drum, the concept of which was ripped from Edward Whistler who was the Jess Briley of the Pigeon Ring in the 19th century.

    Brister and Briley had a rotating pattern board that lived at the Greater Houston Gun Club in the late 80s, but by then I think everybody had about given up on trying to recreate physics and shorten a shot string.

    Tula had the best success (if I recall what Briley said), managing to shorten the string about 4", on average "... but the first 1/3 is what breaks birds, anyhow."

    ahh ... the joy of half-remembered conversations.


    GS
     
  16. ricks1

    ricks1 TS Member

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    you can get a good idea of how long it is by shooting over water. at normal target range 40 to 50yds its probley less than 3ft. Would be hard to pick sound up like that.When you get out to 200yds that might work. Have you ever shot straight up and listen to the shot fall. that is a loooong shot string
     
  17. Ricky B

    Ricky B TS Member

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    I would go the low-tech route first and see if that works. Put a microphone right by the tin sheet so it can pick up the sound of the shot hitting it. Hook up the mike to a computer. Use Audacity, which is a free, open-source software for recording and editing sounds, to record the sound of the shot hitting the target. Then review the audio file in Audacity on your computer monitor, which should show the sound pattern in graph format. Audacity also shows the time of the sound pattern. You can expand and contract the graph.

    Here's a link to the home page: http://audacity.sourceforge.net/

    By the way, the tin might have echo or some other sound artifact that interferes with recording. If that happens, try using a different medium, perhaps heavy paper that makes a ripping sound. Obviously the area should be quiet (except for the gunshots!) for best detection of the sound of pellets hitting the target. A windy day is not a good time to do this.

    By positioning the mike by the target (40 yards away from the shotgun), you can use a sensitive mike without worrying so much about the sound spike from the gunshot.

    You could check the accuracy of the test by seeing what Audacity shows you for the time interval from the report of the shotgun (allowing for the time for the sound to travel to the target or maybe using a second mike by the shotgun) to the time of hitting the target and then extrapolating from that the indicated velocity. Hmm, the speed of sound adds a complication.

    Per Wikipedia, in dry air at 20° C (68° F), the speed of sound is 330 meters per second (1,083 ft/s). If the *average* velocity of the pellets over 40 yards is less than that, the sound of the gunshot might be recorded first and might drown out the sound of the pellets hitting the target.

    Good luck, and let us know the results.
     
  18. phirel

    phirel TS Member

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    Neil pointed out a flaw in my plan. I would have to have a good measurement of the velocity of the leading and trailing shot. This could be estimated from the velocity of the leading shot and the time for all of the shot to strike the tin sheet.

    My real problem is accurately measuring the time between the first shot and the last shot hitting the tin. I need a simple way to print the sound signature.

    GS- I have tried the rotating disk to measure shot string in the past. My results were between very poor and comical. A six foot disk rotating at 900 RPM has the outer edge rotating 18.85 times faster than the center. Both the math and keeping the disk rotating without flying apart are difficult.

    Pat Ireland
     
  19. hmb

    hmb Well-Known Member

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    Pat,

    I have a solution to your problem. The next time the county fair is in town you can attach your patterning paper to the merry go round. This surely will be an accurate way to measure shot string length. HMB
     
  20. phirel

    phirel TS Member

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    Neil pointed out a flaw in my plan. I would have to have a good measurement of the velocity of the leading and trailing shot. This could be estimated from the velocity of the leading shot and the time for all of the shot to strike the tin sheet.

    My real problem is accurately measuring the time between the first shot and the last shot hitting the tin. I need a simple way to print the sound signature.

    GS- I have tried the rotating disk to measure shot string in the past. My results were between very poor and comical. A six foot disk rotating at 900 RPM has the outer edge rotating 18.85 times faster than the center. Both the math and keeping the disk rotating without flying apart are difficult.

    Pat Ireland
     
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