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How Far to Adjust Rear Sight?

Discussion in 'Gunsmithing and Repairs' started by Homerboy, Aug 12, 2017.

  1. Homerboy

    Homerboy Member

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    I bought a used Ruger SR9C. The rear sight is adjustable and it seems pretty even, but my shots are hitting pretty consistently 3 inches or so to the left. So I have to drift the sight to the right. It's kind of a hassle. Loosen screw and tap with plastic hammer. So how far do I want to drift the sight to start? I know I'm gonna have to bring the tools to the range to get it right but just want a starting point.

    I've been shooting for a long time, so I don't think it's shooter error. Semi autos and revolvers.
     
  2. sbwaters

    sbwaters Member

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    Mine was shooter error. Hard to believe. Watch how you grip and watch how you pull the trigger.

    Ask someone else to shoot it as a check.
     
  3. 243winxb

    243winxb Member

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  4. Kp321

    Kp321 Member

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    Dawson Precision has a handy sight calculator on their web site. It is designed to calculate what front sight height is required but the data can be used for windage adjustments too.
    Before starting, make a mark on the sight and slide with a colored pencil, I find that silver works well, so you have a reference to see how much you have actually moved the sight.
     
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  5. Varminterror

    Varminterror Member

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    Ya got two hands - that's about all it takes to eliminate shooter error as a culprit with a handgun.

    3" at what range? A guy can do the math to figure out how far to drift, almost, just need to know the exact distance to the target, exact sight radius, and exact distance you need to shift.

    (drift distance in inches) = (distance needed to shift on target in inches) / (range in yards) / 3 / 12 * (sight radius in inches)

    The problem, of course, is you'll be moving the rear sight on the order of thousandths of inches to make the shift. A 3" shift at 10yrds with a 4" sight radius only needs 33 thousandths drift on the sight.
     
  6. Homerboy

    Homerboy Member

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    About 15 yards.

    And I do hand load. But I get the same results with factory ammo as my hand loads.
     
  7. GRIZ22

    GRIZ22 Member

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    I didn't calculate it but 2/3 of an inch sounds like he'll run the sight out of the dovetail.
     
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  8. 243winxb

    243winxb Member

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    sightcorrection.JPG I did say
    :oops:
     
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  9. boom boom

    boom boom Member

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    Thanks for posting the link--Brownells has some unique and useful free articles and stuff tucked away on its website. Now, I am probably going to go there and order something darn it.
     
  10. boom boom

    boom boom Member

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    I would go a step further than Kp321.

    Sometimes when you move a sight in the dovetail which hasn't been moved, the dovetail loosens a bit and the sight can migrate just enough to create a headache. After you get the rear sight where you want it, mark semi-permanently with fingernail polish or whiteout typewriter correction fluid the location with a line so you can tell if it is moving around at a glance. If you are sure that you won't adjust the sights again, some folks peen or stake the rear sight or the dovetail just ever so slightly on both sides to prevent movement. It doesn't take very much or you can use some variant of loctite that is removable with hand tools. Make sure to have the right tools to do the job. EDC weapons and hunting firearms in particularly have this problem because of the movement and banging around they go through versus a range gun.
     
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