Up / Downhill shooting

Discussion in 'Tips, tricks and tutorials' started by greytemples, Jan 22, 2013.

  1. greytemples

    greytemples Member

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    Hello everyone.

    I tried a search for this topic on the site but cant find anything that covers this in detail.

    I've looked at various other sites covering the subject but not specifically for air guns.

    Is there a guru hereabouts that can tell me how it practically affects FT or HFT shooters ?

    Cheers

    PS is there a max angle for field target setters?

    Sorry if these are newbie questions :eek:
     
  2. NJR 100

    NJR 100 Because I`m AWESIME !!

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    No, no max dangle.
    You dont see too many really high or steep low shots in Uk shooting. Seems to be far more common a shot in Europe though.

    Basic rule is if its very steep high or low, aim low, but dont worry too much about in in uk.
    If you new, you have far more flat sitters to hit then the standers and kneelers before worrying about Euro targets.
     
  3. DaveRobinson

    DaveRobinson NEFTA Chairman

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    Heyup Sii this lads from Yorkshire he will be coming across plenty of up n down hill shots lol especially if he went to anston wl sunday
     
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  4. maestro

    maestro European Champion 2018

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    As a rule of thumb:
    - Below 15 metres do nothing,
    - Below 15 degrees do nothing,
    - For the rest aim a bit low but still inside, for very far away and very high/low placed targets even below the kill.

    Calculating cosine values works only beyond the top of trajectory (and not too precisely), never use it for the closer ones.
     
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  5. DaveRobinson

    DaveRobinson NEFTA Chairman

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    Where abouts in yorkshire are you fella best thing to do is get along to a club in the yorkshire area look at www.nefta.org.uk

    TBH from my experience nobody can teach you what to do there's no books of dos and dont's what suits one dont always suit another get along get some practice in theres more to learn in your skills to start with than worrying about inclinometers and all that.

    Hope this helps
    Dave
     
  6. hotversion

    hotversion Member

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    Try going to emley moor mate,theres theres more up n downs than a tarts knickers.:D
     
  7. CameronWilson

    CameronWilson Member

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    Not scientific... but I was always told that if a target was up a tree, it was actually further away than the base of the tree. The same is true of a target at the bottom of a valley.

    So whether you have to aim further up or down depends on where the true distance to the target appears on your pellets trajectory.

    The course builders know that a lot of people just look at the base of the tree, and assume the target itself is the same distance away.

    Cam.
     
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  8. greytemples

    greytemples Member

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    Cheers Dave

    I'm a club target shooter - paper targets at 20 - 25 yards but I'm going to give FT / HFT a go. I contacted Redfearns a few days ago but the chap that responded said I should get back in touch in a few weeks to see if there was any room for a newbie

    I'm actually in the Keighley area so a bit of a journey to Redfearns.

    Anyway, thanks to all for the responses and I look forward to seeing you at future shoots.

    Cheers

    Steve
     
    Last edited: Jan 25, 2013
  9. Ceathreamhnan

    Ceathreamhnan WHFTA Champion 2013

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    You can put in the angle to the target in Chairgun and see the change in POI.
     
  10. RobF

    RobF Administrator Staff Member

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    I can bore you with the technical details... :D

    In short, if you range to the target, the actual range gravity acts on is a cosine of the angle to the target multiplied by the range to the target, which will give you the range to dial in. Got that? :D

    So for a 45 yd target, you measure the angle to it, say 25 degrees up, and the cosine of that is 0.90... multiply 45 by .90 and you get 40.5 and that's what you should dial. Doesn't matter if it's up or down, the effect is the same. (that's where the explaination can get complex..;))

    But 25 degrees is difficult to hold position on, even sitting... it's very steep and most people over estimate it.

    You can get very expensive or cheap cosine indicators, you can make one yourself with a nail and some markings...

    Only one or two targets i found it worth taking 10% off last year, think that was NWFTA GP and WAFTA GP, each were small reducers around 8-10 yds. On a 15mm you can miss because the 10 yd had to be dialled at 9, and the 8 yd just needed 7 which i dialled the wrong way as a guess and missed. (You can lead a horse...)

    This is a cheap one... look up SlopeDoper.com

    [​IMG]

    But there are expensive ones which tell you the same info but clip on to scope rails like spirit levels, called cosine indicators

    They'll be banned in HFT no doubt, which relies less on technical addons than FT does.
     
  11. maestro

    maestro European Champion 2018

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    Rob, this cosine thing works only beyond the top of trajectory but not at all for the closer targets. Imagine a target at 13 yards, if you multiply it with the cosine and set your scope to the 12 yards clicks then you'll aim higher instead of aiming lower...

    The amount which you have to aim lower is the difference of pellet drop at 13 yards (muzzle-to target distance) and pellet drop at 12 yds (horizontal component of the distance). Calculating with horizontal distances is an acceptable approach for longer ranges, but is a suicide for the closer targets because you compensate into the wrong direction with this method. The proper way is to set the scope to the measured distance (13 yds in my example) but aim lower with the needed compensation. Chairgun can give you the compensation in centimetres or even in clicks.
     
  12. Mr P

    Mr P Active Member

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    Try this post "different aim on vertical plane"
    regards steve
     
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  13. simona

    simona Active Member

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    Maestro is right, at very close range we are essentially dialing to correct for the bore/sightline offset rather than just pellet drop, this large offset overprints the tiny variation in drop between ranges. The difference in actual pellet drop between say 13 yards (line of sight) and 12 yards (cosine) is so small as to be almost nonexistent.

    At longer range in practice it's very rare to need to allow more than 1/2 MOA of compensation for angle. The most I have ever allowed is, I think, 1 MOA in Italy on one or perhaps two shots, 53-54 yard targets placed super high on a hillside.

    Rather than trying to estimate the angle of the shot I tend to go for estimating the target's vertical offset from my firing point and then using Pythagoras to work out the length of the adjacent limb of the triangle; as I have the hypotenuse through range finding and an estimate of the opposite limb.

    I spent years estimating the height of seabed objects from sonar data using a similar triangles method which has given me a largely unwanted inbuilt directory of various hypotenuse (aka line of sight) vs. adjacent (ballistic distance) triangle side lengths. This is occasionally useful in estimating how many yards short of the line of sight distance I need to be knocking off. Generally though I say sod it and just take one or two clicks off.

    If you just took 1/2 MOA off when you were sure a target was significantly steep and past 15/20 yards off and 3/4 MOA off when so steep that you can almost not manage to point the gun at it, then you won't be far off.

    In summary no line of sight range assessment will ever be less than the distance traveled by the shot perpendicular to gravitational acceleration, and only on a perfectly horizontal shot will there be a match.
     
    Last edited: Jan 22, 2013
  14. RobF

    RobF Administrator Staff Member

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    Yes but if you shoot at a 13m elevated or declinatec target then the effective range is 12 yds so the pellet only will drop the distance over 12. If you dial 13 your shot will go low. It reverses the effect because its the range that is lowered not the flight of the pellet. That doesn't change just the distance in the horizontal plane it travels. If you fire vertically up at at 10yd target the target never drops but stays straight up in flight and never converges with line of sight of scope. Dialling 10 yds would never work. Dialling the cosine of 90 degrees which is zero would work because you'd dial in 0 yds ( if that was possible )

    It's been a long day but before the top of your trajectory the pellet will appear to fall and after rise. Around the top it won't do a thing. 10% less of 30 yds is 27 yds which for me is the same clicks.

    Try it on paper and see what happens.
     
  15. RobF

    RobF Administrator Staff Member

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    Agreed Simon its rare to need to do it and Italy was only one place where I wish I had. Did the same aimed at bottom of kill for those long ones. As you say often you don't need 1/2 as much as expected because we over do our angle estimation.

    For me the difference between say 9 and 10 is massive due to the high scope mount. I think from memory it's something like 4-5 Moa.
     
  16. Brian.Samson

    Brian.Samson Allowed in Sales Staff Member

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    When Bainsey was still with us it wasn't uncommon to see long range targets at impressive angles. A reasonably good rough approximation was to rangefind the base of the tree the target was on and shoot at that range. So with a target that ranges in at 45 yds, if you find rangefind the base of the tree as say 40 yards, you should dial in 40 yards instead of 45. But that's only for the ones further than 25 yards.

    I remember one year at the Anglo American, Bainsey set out a vertical target - that was erm... Interesting :)
     
  17. blackscale

    blackscale Member

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    I think the pellet will strike higher on the closer shots if inclined as well.....:rolleyes::D
    Can't see it hitting lower than your 'dialled' range....
     
  18. PaulD

    PaulD I like Feinwerkbau's

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    Maybe I'm missing summat here (usually the target:eek:o ) but why range the bottom of the tree on an elevated target? I range on target and then aim in the bottom of the kill:confused: I don't miss that many high/low targets and when I do its because of either poor wind judgement or wobble. Methinks you can over complicate things ;)
     
  19. Conor

    Conor Never been banned from sales Staff Member

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    Soh cah toa

    Best post I've read in years Simon! Simple yet effective.
     
  20. Brian.Samson

    Brian.Samson Allowed in Sales Staff Member

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    Well, because it gives you a reasonable rough approximation of the click correction you need to make to adjust for the elevation and its a lot less maths than figuring out cosines and estimating the angle.

    Is rangefinding a tree really that complicated :confused:
     

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