ProTarget Scope rail

Discussion in 'General Airgun Chat' started by rubi-tong, Nov 20, 2009.

  1. rubi-tong

    rubi-tong Bernies MY *****

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    Hi all, I've just purchased a ProTarget for use in HFT, is there any way I can get a scope on with the "rail" removed to get a lower scope line.
    I thought about a Sportsmatch Low up front and a Medium in the back, it apparently measures 3.25mm difference front to rear and these mounts have a 4mm in height difference. Would it work, or is 0.75mm too much.
    Regards, Mark
     
  2. MAJOR 47

    MAJOR 47 New Member

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    I used a sportsmatch high at the back and a promount medium at the front, less variation between them, photo negative on the front mount trues it up.

    Still got the other odd two if you want them.

    Jon
     
  3. Weevie

    Weevie Banned

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    I've asked about this and the general opinion seems to be that the scope rail should be left on as it stiffens the action.

    Dave Ramshead still has his scope rail on and he does okay with his when he uses it.

    I did okay at the Gathering (57) and I'm hardly a masterclass in shooting. :eek:

    I heard some people have had their rails skimmed to take a bit off, although I'm not sure how that'd be done.

    I've got some BKL 30mm low mounts on mine so while it's higher than usual it's not that much higher and I'm getting used to the close up aim-points.

    I love my PT, mine's the short action. It may not be the perfect HFT rifle scope height wise but it just feels so nice in the hand...;)
     
  4. Dave Ramshead

    Dave Ramshead England HFT Team squatter

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    Going for a very low mount set up is very over rated imho - makes the longer shots harder, it's a better benefit to have a slightly higher set up and keep the rail.

    I use low mounts (for scopes upto 32mm obj), which gives me a scope to barrel centre of 1.82" - which is the same as an s400 on high mounts.

    With these mounts, the objective bell end sits below the rail.
    see here: http://elmerfud0-0.piczo.com/?g=55046164&cr=5

    The biggest negative point of ditching the rail is risk of damaging the dovetails on the block, which you really don't want to be doing;)
     
  5. Sam Vimes

    Sam Vimes New Member

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    I'm with Dave on this one although I've long suspected that we are in the minority. Far too many folks rush headlong into mounting scopes as low as possible without really thinking about what they are doing. On a rifle without an adjustable cheek piece I can almost understand it, on a PT I can't. Leave the standard rail on the rifle and accept that you won't get the scope quite as low as many would wish. If you really want to mount a scope lower on a PT then look to low mounts and a scope with a 1" tube.;)
     
  6. Weevie

    Weevie Banned

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    I think the reasoning behind this low mounting for HFT is that for longer shots you get the luxury of a 35-45mm KZ; many longer shots (although the Gathering at Emley gave the lie to this :D) are 40mm.

    15mm KZ targets can be between 13 and 25 yards. When your scope is mounted relatively high this gives quite a wide range of aimpoints, add wind into that and it can be quite awkward.

    With the BKL lows that you kindly sorted for me my scope is about 1.86" high. I'd not want to go much higher than that for HFT.

    With my scope setup and my pellet velocity and notional BC I get the following aimpoints from Chairgun Mobile (I'm posting from my Linux setup so I haven't got access to Chairgun 2 and so it may not be quite right but you get the idea)

    13 -0.36
    14 -0.16
    15 0
    16 0.12



    So between 13 and 16 yards that's 5mm odd difference, which leaves you 2.5mm from the top of kill. With a bit of an updraft that could mean the difference between a kill and a splitter that leads to a plate.

    ...
    ...
    ...

    Hmmm...interesting.

    I've just done a comparison with a 1.5" scope height (which IIRC and I may not, is about what it was with medium mounts and an S400) and the aimpoints between 13 and 16 are obviously different from a 1.86" scope height (they're a bit higher)...

    ...but the gap between 13 and 16 for a 1.5" scope height is about the same as with the 1.86" scope height. :eek:

    I've left the post as I originally typed it to show that it's easy to accept received wisdom that turns out to be completely wrong! :eek:

    So in conclusion then, Chris and Dave are absolutely correct. Get some lowish mounts and leave the scope rail where it is.
     
  7. rubi-tong

    rubi-tong Bernies MY *****

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    So your saying that there is no difference (neglectable) between 1.5" scope height and 1.8" scope height. I'm trying a Hawke 2-7x32 map6 over the winter, to mainly find out if I can do away with my bracketing and start estimating by eye.
    My belief was a lower scope flattens your trajectory out slightly, is this incorrect?
    The front of the Rail on the PT is not very deep so i think i may just keep it on ,as taking it off, I'm not going to gain as much as I first thought.
    Thanks for the advice guys, keep it coming if you have something to add.
    Regards, Mark
     
  8. Sam Vimes

    Sam Vimes New Member

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    It'll help at close range at the expense of the long range. There's a happy medium that can be had. The best way to see what's what without actually messing with your scope is to use chairgun. I always prefer a scope to be a little higher than is in vogue. It's harder to rangefind accurately at longer ranges so I'd prefer leeway at distance rather than close in. However, close in is where you are likely to see the reducers. Swings and roundabouts, you need that happy medium.;)
     
  9. Dave Ramshead

    Dave Ramshead England HFT Team squatter

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    Guy's, I wouldn't want to make close ones any harder than they need to be, but don't get hung up about hitting them in the middle. This reduces the amount of aimpoints you need;)

    On my 1.82" set up (only 1mm lower than your 1.86" set up weevie) I have 1 aimpoint regardless of whether the target is 8y or 12y. Spend some range time on the close ones and it will become clear;)
     
  10. Weevie

    Weevie Banned

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    Well there is a difference. The aimpoints are higher with a 1.5" scope height but the gap between the various aimpoints (say for example the gap between 13 and 16 yards) is, according to chairgun mobile at least, pretty much the same between the two scope heights.

    That is to say, for example, the gap between the aimpoint for 13 yards and 16 yards (with my pellet velocity and BC) is pretty much the same for 1.5" scope height as it is for 1.86".

    I guess the effect of scope height on 'flattening' the trajectory at closer distances (at least as far as HFT is concerned) has simply been exaggerated by received wisdom.

    I'll check this on Chairgun 2 in a sec (means restarting my PC and booting XP up) and post the results.


    Right. Just checked this in Chairgun 2. Here are the results. This is 775 fps with a BC of 0.0210 (see climate change chappies? Sharing your data isn't that hard!)

    POI difference between 8 and 12 yards (not such a biggie, mind you, since in UKAHFT at that range the KZ that must be 20mm or greater):

    For 1.86" scope height: 0.435" (or 11.04 mm)
    For 1.50" scope height: 0.394" (or 10.03 mm)

    Aimpoints are 1.1 mm closer together with 1.50" scope height than with 1.86" scope height

    POI difference between 13 and 16 yards (more important as this could be a 15mm KZ in UKAHFT):

    For 1.86" scope height: 0.236" (or 5.944 mm)
    For 1.50" scope height: 0.205" (or 5.207 mm)

    Aimpoints are 0.737 mm closer together with 1.50" scope height than with 1.86" scope height

    So, a flattening of trajectory of just over three quarters of a millimetre for the really cruicial distances and only just over one millimetre for the less cruicial ones

    Even if we go mad and say you can't tell the difference between 17 and 24 yards there's still only a difference of 1.9 mm between the gap between the aimpoints for 17 and 24 yards at each scope height. At those ranges you're aiming in the bottom half of the kill anyway so...

    Assuming chairgun's correct (and it tends to be reasonably on with trajectory calculations) there really is no advantage in taking the scope rail off. Just get yourself some low mounts and you'll be fine
     
    Last edited: Nov 23, 2009
  11. Sam Vimes

    Sam Vimes New Member

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    B-Squares not BKLs. You had me puzzled for a while there!:eek:;):confused::D
     
  12. Weevie

    Weevie Banned

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    Oh yes, that's right...they're just the job anyway! :eek:
     
  13. richardio123

    richardio123 Member

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    There is a guy called Andy Lawrence who can custom build scope rails even with bullet drop, andielaw@freenetname.co.uk He makes raiser blocks and all sorts of stock accessories.

    R
     

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