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ZEROING ISSUES

bugeyed_99bugeyed_99 Member Posts: 2 ✭✭
edited November 2010 in Ask the Experts
I have a millett LRS 6-25 scope mounted on a mossberg 4x4 .338. when i zero at 100 yards and go out to 200 yards instead of shooting 3.4 inches low like it should at 200 it shoots 6-7 inches high. im using winchester ballistic silvertip 200gr. any ideas? One guy said the back base might be lower then the front base. any auggestion would be great

Comments

  • tsr1965tsr1965 Member Posts: 8,682 ✭✭
    edited November -1
    bugeyed_99,

    Hello, and welcome tot he forums here on Gunbroker.com.

    First, make sure you are holding the rifle down, and not flinching. Try having someone else shoot the rifle. I would also make sure that the action screws that hold the rifle in the stock are properly torqued down to 50-60 inch-pounds. If the front screw is not tight, it could let the barrel continue to rise under recoil.

    Best
  • wpagewpage Member Posts: 10,201 ✭✭✭
    edited November -1
    Contact the manufacturer of the scope.
  • MobuckMobuck Member Posts: 14,059 ✭✭✭✭
    edited November -1
    If you are sighted with POI @ 100 yards, it is impossible for the bullets to strike high @ 200 yards unless some other factor is involved. If you hold the rifle the same way and counter recoil the same, the different distance will not cause the impact to rise. Are you using the same X setting? Some scopes will change impact when the magnification is changed although this is not something that should happen in a good quality scope. Did you reshoot @100 yards to verify that the zero had not slipped?
  • perry shooterperry shooter Member Posts: 17,105 ✭✭✭
    edited November -1
    Hello one thing many people forget is The higher the center of sight-line of the scope compared to center of Bore line the farther apart the 2 places the flight of the bullet crossing the point of sight will be with This large of scope I assume the scope rings are very high This could cause your affect. The bullets flight is an ARC.draw two pictures with this same arc. "Use a dinner plate to draw this line same as bullet path. now draw 2 straight lines this is sight line start one line slightly above the arc and one at a greater distance above the arc and have both lines cross the arc about 3inches from starting point . now look at where the straight line crosses the line the second time . the bullet will be above the line of sight between this first and second crossing the higher it starts out above the arc the further it will be between these 2 crossings. the bullet in your case is crossing the line the first time and then it is crossing from below and the second time it crosses it is from above. you may have a setup that could have POI right on at 100 yards and then also right on at 300 yards.
  • dcs shootersdcs shooters Member Posts: 10,870 ✭✭✭
    edited November -1
    Go to www.winchester.com and use the ballistics calculator for your load.
  • rsnyder55rsnyder55 Member Posts: 2,526 ✭✭✭
    edited November -1
    Perry is right. Also most charts I've seen are based on the line of sight being about 1 1/2 inches above the bore so it the center line of the scope is higher then this, it can make a difference.
  • babunbabun Member Posts: 11,038 ✭✭✭
    edited November -1
    For the shots to be that high after another 100 yards your scope would have to be about
    8 inches above the bore. Are you sure you don't have about 10 to 20mins of slant built into that scope base?? Something is basically wrong with your set up if nothing is found loose.
    Go here and use the calculator after you read the story. http://www.hornady.com/ballistics-resource/external Bob


    PS... with a scope 4 inches above bore, a normal load for the .338mag will be close on at 100 and 200 yards. I know your scope ain't 6 1/2" above bore.........
  • midnightrunpaintballermidnightrunpaintballer Member Posts: 2,233 ✭✭✭✭✭
    edited November -1
    I'm gonna have to second the vote to shoot again at 100 to confirm zero is still correct.

    Also, I'm curious, you say at 200 it's 6-7" high. Is it just throwing a few up there from time to time or is it printing the whole group there? Are you shooting across flat ground or across a valley or something where there could be a draft coming up and blowing your rounds off? At 200yds, it wouldn't take a whole lot of wind to do that...
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