Sighting-in issue

Discussion in 'Optics & Mounts' started by farmer12, Apr 19, 2012.

  1. farmer12

    farmer12 New Member

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    Hey guys,

    Ive been lurking around for almost a year but just now decided to set up an account. Recently I purchased a S&W M&P 15 along with a 3-9x40 Weaver scope. Since I have installed the scope, I have had hell getting the gun sighted in. At 40yds, I couldnt hit the paper at first. Today I finally had it hit center but with the next shot, it would hit as high as 3-4in. The scope(or rifle for all I know) is wanting to shoot high and right and I have tweaked the adjustments so much that Im in a world of pissed off. So with all you can gather from that, would you say is the issue? Gun, scope or shooter? Other than continuing to be patient with it, Im at a loss. I appreciate any help I get.
     
  2. mountainman13

    mountainman13 New Member

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    My guess would be a little bit of all of the above. Check your scope mounts make sure they aren't loose. I'd recommend getting a laser bore sighter ($25 or so at walmart). Zero in the scope with it and take it to the range. That should get you close and you'll be able to tell if it is the scope,gun or shooter that is the issue.
     

  3. unclebear

    unclebear New Member

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    you need to make sure everything is nice and tight, I had the same problem with a marilin 30-30 my front mount wasn't screwed down tightly. Also you can over tighten scope mount and hurt the glass or your glass might just be crap sometimes it happens.
     
  4. farmer12

    farmer12 New Member

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    Now that you mentioned it, I did have to tighten down the mounts to the receiver after my first day sighting since they were quite loose. Once I had them snug, things really started getting worse. Is there anyway to tell if it has something to do with your glass? I know Weaver isnt top of the line but I wouldnt think they would have much problems with that.
     
  5. mountainman13

    mountainman13 New Member

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    Not that I know of. You may want to take the scope off and re-attach the mounts with some thread lock. Double check the alignment on them and put the scope back in and then bore sight etc.
     
  6. Dearhunter

    Dearhunter Supporting Member Supporter

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    Sighting in a scope

    OK, check and make sure scope is installed correctly. Make sure all screws are snug and tight.
    Now, take a white piece of cardboard, poster board, or art paper approximately 18 X 18 inches. plus or minus. Take a yard stick and draw a solid black line in the center top to bottom, same thing side to side. Now you have a big cross on your paper. MAKE SURE YOU USE A GUN REST.
    Take a friend with you to sight in. Line up you scope cross hairs or dot on the center of the target where the lines cross. Hold that spot, squeeze trigger till gun go's off. Now see where it hit paper. NOW, this is where your friend comes in. take covers off your elevation and windage adjustments on the scope. Line up your scope where you had it before. NOW, hold that position and do not let your rifle move, have your friend GENTLY dial your scope up and down while you give him directions till you have the cross hairs on the spot where you bullet hit.

    Your scope is now zeroed in. Now shoot again lining up on the center of the target and slowly SQUEEZE the trigger till it gos off. DONT MAKE YOU GUN GO OFF, LET YOUR GUN GO OFF!! You should hit dead center.
     
    Last edited: Apr 20, 2012
  7. mountainman13

    mountainman13 New Member

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    Yeah I guess you could that if you want.
     
  8. farmer12

    farmer12 New Member

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    Thanks DH. I will certainly try this tomorrow!
     
  9. mountainman13

    mountainman13 New Member

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    Good luck. Let us know how it works out.
     
  10. JTJ

    JTJ Well-Known Member Supporter

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    I see a couple of possible problems. Your scope is parallax set at 100 yards. At 40 yards you may be getting parallax error. Repeatable cheek weld is everything. Your head and eye have to be in the same place for every shot. Even slightly off can shift the poi. Are you mounting to a flat top receiver? What kind of mounts are you using and are they set to center with the irons? Centering to the irons is the optimal height to the center of the scope. You may need to go to a forward offset mount to get proper eye relief. on the picture, the scope is on a forward offset 1 piece mount and is set to center at the height of the irons if they were there. the cheek weld is exactly the same as for the irons and is repeatable.
     

    Attached Files:

    Last edited: Apr 19, 2012
  11. mountainman13

    mountainman13 New Member

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    Now that's some good input. I wasn't even thinking about parallax.
     
  12. farmer12

    farmer12 New Member

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    JTJ, I think you hit the problem. First off, my cheek weld is not the same everytime. The AR came optic ready. When I ordered some Weaver mounts, I didnt realize they were very short. Everytime I prepare to aim, I have to squeeze my face against the rail to have an adequate look through the scope. ESPECIALLY when I adjust to a stronger power! So with that all said, thats probably the issue. I have already ordered high mounts(same product). Ill try to post a pic tomorrow so you have an idea. Gathering from one I mentioned, would you think that may fix my issue?
     
  13. ryguy00

    ryguy00 New Member

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    shoot 3-5 shots BEFORE and in between making any adjustment on the scope. If your ammo is crappy, or the gun is moving around because of a bad rest or a lack of a rest or shooter error or whatever, or there is whatever problem causing the gun to not be able to group well, then you will be chasing bullet holes forever with your scope adjustments if you only shoot one round and adjust.

    make sure all hardware is snugged. do not overtighten. use blue loctite. boresighters from walmart are awesome but the lasers are hard to see in broad daylight. easy solution: boresight at night, then fire on paper the next day. remember the shooting fundamentals. trigger control, breathing control, etc. consistency is key! put the gun in the same spot in the rest, grip with the same pressure, cheek in the same spot, trigger in same spot on your finger, etc. do everything EXACTLY the same for EVERY shot.

    if you're still having a hard time getting zeroed, then shoot a group with iron sights or a borrowed scope. don't worry about making adjustments as long as you're on the paper. it doesn't matter where the group is, it just matters how tight it is. you can make adjustments later to move future groups to where you want them. if the groups are terrible with scope and good with irons, then you have a bad scope or something wrong with the way it's mounted. if groups both ways are terrible, then you have a problem with your ammo, the gun itself, or your technique. if the groups are better with the scope than the irons, but they're still terrible, then you really need to work on your technique. at 40 yards, you should be putting 5 shots into one ragged hole. or very close to it.