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Bullet drop issues

Discussion in 'Rifle Country' started by zstephens13, Jun 12, 2011.

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  1. zstephens13

    zstephens13 Member

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    So on my AR, 16" barrel .308 caliber, I have a 3-12 scope. Yesterday I was shooting at 112 yards and 248 yards. At 100 yards the bullet hits right on, at 112 it hits an inch low. The surprising thing is that it hit 12" low at 248 yards. I don't think the bullet could be dropping that fast. Could it be the way I have my scope sighted in? Like at 100 yards the bullet arc is hitting the line of sight and dropping from there?

    I am shooting German Surplus DAG ammunition, FYI. I heard that stuff is loaded pretty hot so I should expect some pretty good velocity.

    Help me out.
     
  2. D*N*R*

    D*N*R* Member

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    At 250 yrds. 8 in. sounds more like it. Probably your short bbl to blame. Im sure you didnt buy a 308 win.-dsock for its flat trajectory anyway.
     
  3. wanderinwalker

    wanderinwalker Member

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    Uh, what's the issue? You're shooting a short-barrel rifle with what I am going to assume is typical 147-150gr FMJ .308" bullets. It's not exactly a flat shooting combination.

    Point: For 200-yards, I figure 2-clicks up from a 100-yd zero (1-2 MOA, so 2-4") and 300-yards is another 3-MOA from there (9"). And this is with a 20" barreled .223 with 69gr bullets at 2850 fps. The come-ups are about the same for standard M2 Ball in an M-1 Garand or for the M1A-14 type shooters as well.
     
  4. zstephens13

    zstephens13 Member

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    I guess I just didn't expect the bullet to fall so fast.
     
  5. mrbro

    mrbro Member

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    150g fmj, muzzle velocity of 2400fps, drop at 248 yds is 12.1 inches with a zero at 100 yds. Perfectly normal.
     
  6. zstephens13

    zstephens13 Member

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    Thank you mrbro, I appreciate the reassurance. I was mostly just wondering if that was right or something was wrong. What range would you recommend to zero a load like this?
     
  7. Dr T

    Dr T Member

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    Three inches high at 100 yards--then you will have a 200 yard zero and about 11.5" low at 300. Don't worry about it.
     
  8. TonyAngel

    TonyAngel Member

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    Or you can learn your equipment and dial for elevation.
     
  9. EdLaver

    EdLaver Member

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    I set my AR10 carbine with a 50 yard zero and left it alone.
     
  10. BullfrogKen

    BullfrogKen Moderator Emeritus

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    My range cards for my 3 different .308 loads, all with 100 yard zeros:

    110 gr V-max at 3100 fps - 2.5 minute adjustment at 250 yards = 6 1/4" drop.
    155 gr Scenar at 2950 fps - 2.0 minute adjustment at 250 yards = 5" drop.
    175 gr SMK at 2650 fps - 4.0 minute adjustment at 250 yards = 10" drop.

    And I'm using a 26" long barrel. Your velocity is going to be a lot less than mine.


    So, the next time someone tells you a story about the deer he shot at 400 yards and only held the crosshairs on the top of it's back to hit it . . . now you know something's not right. Either it wasn't at 400 yards like he thought it was. Or he missed. Or he's just plain lying to you.


    Exactly.


    I've seen guys come out to the range with expensive scopes and nice adjustment turrents, but never, ever try to even attempt to learn how to make that equipment work.


    Scopes these days all have nice adjustment knobs that are, for the most part, reliably repeatable. What make and model of scope is it and what are the adjustment knobs?
     
  11. MtnCreek

    MtnCreek Member

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    I guess everybody has heard those stories. I shot a doe with a 30-30 at +/-250 yds, perfict shot right where the neck meets the head. Only problem, I was aiming at the shoulder! Friend of mine shot a doe in the head w/ a 30-06 at over 300 yds; it took a few days before he would admit that he wasn't aiming for the head! Both instances were pure luck experienced by dumb kids.

    Op, Check out handloads.com. They have a good BDC tool.
     
  12. TonyAngel

    TonyAngel Member

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    You could also check out the ballistic program on hornady.com
     
  13. gamestalker

    gamestalker member

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    You need to find your zero point for the bullets velocity and B.C. first. then you'll know with some certainty where line of sight zeros with your bullet path. For instance, my 7 mag. shooting a bullet at 3400 fps MV with a bullet that has a BC of .4 will zero at about 343 yds., thats just an example not actual ballistic fact. This is what you need to figure out other wise you'll have premature bullet drop or other odd performance issues within the first 300 yds. or so, depending on the MV and BC your dealing with.
     
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