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Thread: FT scopes - why so high?

  1. #1
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    FT scopes - why so high?

    I was watching some airgun related item on YouTube, which ended, and before I could select something else, coverage of a World FT Shoot came on. Now I don't shoot FT (or HFT for that matter) but I was amazed by the distances that existed between barrels and scopes; some looked as if I could get the palm of my hand in there, upright, and then some! Consequently I noticed that cheek pieces are wound right up on what appear to be huge posts, to enable the eye to address the scope. Now I was always told that the scope should be as close to the centre line of the barrel as possible, so why these huge gaps on FT rigs, and is it the same in HFT? It seems to have nothing to do with the size of the objective lens, as high mounts seem to be mounted on high platforms mounted on the guns' scope rails. Forgive me if this is a stupid question, as I have no experience of either discipline.

  2. #2
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    FT especially allows side wheel.scopes to rrange find.
    This means high mag scopes are used to get a very narrow depth of field.
    The business end of the scope will usually be 56mm diameter so it need highe4 mounts to clear a barrel.
    There are other reasons but essentially high mag la4ge objective scopes need clearance.
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  3. #3
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    Many FT courses have most of their targets set at 30 yards or more, and national competitions might have very little under 40 yards. At these distances the pellet is usually falling away from the high point of its flight.

    Having the scope set high means that your line of sight is closer to the flightpath of the pellet than would be the case with low mounts. Closer means there is a bit more tolerance on rangefinding, if you get it somewhat wrong then you still might get a hit.
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  4. #4
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    It’s the most comfortable head position when sitting. When setting up a rifle from scratch the scope is the last thing I put in place, the cheekpiece is set first and then I match the scope to that.

  5. #5
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    ^^^ Wot Rob sed ^^^

  6. #6
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    Shootfish,

    It allows having a more symetrical far & near trajectory either side of the zero point.

    With the scope close to the bore, the near trajectory is quite flat, whereas the far trajectory will show a lot of drop.

    With the scope mounted higher, the near & far trajectories start to have similar profiles. Ultimately, this will mean that you have to dial in less correction at the longer ranges.

    With a suitable zero range (highest point in trajectory), both near & far trajectory corrections will all be postive, and reasonably symetrical.

    The below shows scope height of 1" (red) and 4" (green) - you can clearly see the difference in trajectory.



    Have fun

    Best regards

    Russ

  7. #7
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    As above, but to condense:

    A low mount means a "virtually" flatter trajectory at close distances, so less over/under allowances to be made.

    A high mount means a "virtually" flatter trajectory at greater distances, so less over/under allowances to be made.

    "Virtually" because obviously a trajectory is unchanging, but when you alter scope height you alter where the line of sight and the trajectory intersect.
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  8. #8
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    It's not to do with clicks. That's a side benefit and it's not that big of a deal.

    If you put in a scope height of 3cm (which is almost on the barrel for a 56mm scope) you get 8 1/4 MOA clicks between 50 & 55. If you put in 9 cm for a height then you get 5. No one is really going to start with 3, so the actual gain between say 5 (which is 7 clicks) and say 15cm (which is 4 clicks) is only 3 clicks for a 10cm move.

    It makes much more of a difference at closer ranges.

    As said it doesn't change your tracjectory, but changes how you look at it. But closer in the angle of difference is much steeper, further out the pellet is more inline with the line of sight.

    Stick it in chairgun and it will show you all this. But there's no point in putting a scope where it mucks up your position.

  9. #9
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    A scopes ranging ability is also less precise out at 45-55 yards, so it helps to have a flatter pellet path at those ranges, in case you range it a little off. It also means that there will be a far greater difference in the clicks at very close ranges, but a big FT scope can range to a few inches at the shorter ranges.

  10. #10
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    ^^^ Wot Rob sed...agin ^^^

    In summary: It has naff all to do with trajectory, it is all about the muscles in you neck, shoulders and back.

  11. #11
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    Quote Originally Posted by NeilMac View Post
    ^^^ Wot Rob sed...agin ^^^

    In summary: It has naff all to do with trajectory, it is all about the muscles in you neck, shoulders and back.
    Why do shooters not opt to shoot prone then as in HFT, or are they only allowed to sit, kneel or stand?

  12. #12
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    In my case it's because getting up twenty times in a 40-shot comp from a seated position is hard enough, and getting up from a prone position would be exhausting.

    I think most FT shooters will tell you - maybe counter-intuitively - that they find the seated position to be the more stable.

    There's also the consideration that there should be less risk of shooting the grass.
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  13. #13
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    Many thanks for the wealth of information guys; it all makes a lot of sense and I can retire 'well learnt' on this matter. And Russ, the chart was particularly helpful.

  14. #14
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    Yes you can go prone in FT but it's off the elbows with no support for the rifle on a peg or the butt on the ground
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  15. #15
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    Prone and FT ...

    So off the elbows and nothing supported forward of the elbows and butt off the ground in the shoulder.

    That position can be very solid, as seen in 50m prone shooting, with the use of a sling, but in FT the targets are not all the same height from the shooter. So a well set sling would not accommodate all targets from the prone position.

    ... then there's the obstacles in the way to the target ... grass, fallen logs etc.

    I still reckon if someone really put the time in then they could shoot prone with a sling and do really well despite the changes in angles.

    It's probably as much to do with ( as mentioned above ) how comfortable sitting is, on a big padded bag, for the average age FT shooter.

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