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O/T bullets not making sense

Discussion in 'Off Topic Threads' started by bodybuilder, Nov 2, 2009.

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  1. bodybuilder

    bodybuilder TS Member

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    I went to sight in my 25-06 today for the upcoming deer season, I have some 75 grain Ballistic tips that shot 1" high at 100 yards and I tried some 120 grain hollow points and they shot straight but 8" high at 100 yards. Why would'nt the lighter bullets shoot higher than the heavier ones? Now not sure weather to lower it or Leave it alone?
     
  2. 221

    221 Banned User Banned TS Supporters

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    It's called ballistics.....I'd be adjusting the scope to what you are going to shoot the deer with, and I doubt you are going to use 75gr.

    All rifles shoot all loads differently, you have to decide what you are going to be shooting and adjust to it.

    You cannot sight a rifle in and shoot anything else without testing it.
     
  3. hmb

    hmb Well-Known Member

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    There is more than one reason for the results you are getting. When shooting the heavier bullet their is more barrel lift before the bullet exits the barrel. This raises the POI. The increase in the amount the barrel rises is due to increased recoil from the heavier bullet and the 120 grain bullet travels down the barrel slowly compared to the lighter bullet. This extra time allows the barrel to rise more with the heavier bullet. This increases the launch angle resulting in a higher POI. HMB
     
  4. bodybuilder

    bodybuilder TS Member

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    I know you're right and I'll be adjusting it for the heavier bullets but I just thought that was an odd thing.
     
  5. jimrich60

    jimrich60 Member

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    Entirely normal phenonmena. You have to sight in with the load you intend to use in the hunt. Any other load, including one with the "same" bullet weight, may strike an entirely different point of impact, depending on range. This is due to differences not only in weight, but bullet design, including ogive, balance, type of bullet (hollow point, lead point, ballistic tip, or whatever. Diffences in POI may be only an inch or two, or may be many inches. Sight in for the load you are going to use. If you change loads, you have to change the sight in to zero for that load.

    Jim R
     
  6. wolfram

    wolfram Well-Known Member

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    Yep it is very common for lighter weight bullets to shoot lower than heavier ones. A 7" spread does seem extreme though. What you really need to do is shoot the rifle at your intended zero range say 250 yards and zero the turrets then go to your max range (350-400 yards) and see where it hits. You may be suprised at the results, particularly the windage errors.
     
  7. Savage99Stan

    Savage99Stan Active Member

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    I've experienced the same thing. It happens more often with handguns but the answers above are correct. Heavier bullets are normally slower, recoil more and thus give the barrel more time to rise before exiting the barrel. I believe they will begin to drop sooner, however and will ultimately hit lower than the lighter ones....check the drop tables. Figure the longest range you're going to shoot, then pick that zero off the sight in table and sight whatever high the midrange indicates. With most, especially ones like your .25, you can often zero in an inch or two high at one hundred and require no hold over or under from zero to two fifty.
     
  8. Pocatello

    Pocatello Active Member

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    For big game I always follow Jack O'Connor's method - sight in 3" high at 100 yards. With your .25-06 you should be dead on at about 300 yards, and be able to kill a deer with a center chest hold to about 350-360.
     
  9. Shooting Coach

    Shooting Coach Well-Known Member

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    Pocatello has it right.

    Experienced hunters use the "Rule of Three". Three inches high at 100 yards. This gives your firearm a maximum point-blank range, or the range you can shoot to hit the vital area of large game without sight compensation. This will allow you, when shooting this class of cartridge, to shoot from up close to about 290 yards and still hit a 6" circle with no holdover or under. On a deer, hold top of back over the shoulder at 325-350, and even with the ears over the shoulder from 365-380. This last is a longer shot than most folks should try.

    Pretty nifty, huh? This is from a VERY old school, and it works.
     
  10. Chichay

    Chichay TS Supporters TS Supporters

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    The 75 gr bullet, leaving the muzzle at a much greater velocity (compared to the 120 gr) will shoot flatter and hence strike the sight-in target lower at 100yds. Much further downrange, the 120 gr's superior ballistic coefficient will cause it to travel faster than the 75 gr bullet, and fall less from line of sight. I'm assuming the bullets are both spitzers.
     
  11. Brian in Oregon

    Brian in Oregon Well-Known Member

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    I saw this with both my 223 and 22-250 Browning 1885 Single Shot High Walls. The heavier bullets impacted higher on target because they were in the barrel longer. It really made a noticeable difference because these barrels are 28" long. Also saw the same thing in my Browning 1885 in 25-06, though it had a 30" barrel.
     
  12. bodybuilder

    bodybuilder TS Member

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    thanks guys, You're comments made sense to me!!
     
  13. slic lee

    slic lee Active Member

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    If I were you I wouldnt believe much whats written above.
    Each bullet weight will have a POI at a different location if shot from the same gun if your shooting factory ammo.
    A hunter will decide what bullet weight is needed for the animal he is going after.
    He will then go to the range and shoot only that ammo he will use to hunt with and zero in his rifle depending upon the distance he thinks he will shoot the animal at.
    If for example he is after white tail deer the shooting will usually never be more than 100 yards, usually less, because of the heavy cover they are found in so you would zero the rifle to shoot at 100 yds just in case. You should however after zeroing the rifle at 100, then waiting for the barrel to get cold,shoot at 25 yds and 50, each shot with a cold barrel to see where it hits so you dont have to guess.
    After getting the POI where you want it,then clean the rifle bore and allow the rifle barrel to get cold, why, because when you get that one chance to shoot the rifle will be cold and the POI might be different cold than when hot.
    However, if there is a chance the shot may be longer we again shoot at a target at 150 yds, remembering the rifle at 100 yds hits the bullseye so at 150 see where it hits, if it hits within 1 to 2 inches you now know you can shoot at anything in that range and hit exactly where you aim.
    Under no circumstances do you shoot any other ammo than that you will use for the game your going after always remembering a different bullet no matter the same weight may not hit in the same POI.
    A 120 grain pointy bullet will not hit the same POI as another 120 grain semi point and the amount of powder will also be different in another kind of ammo.
    You only may get one chance to shoot,why not know exactly where your going to hit.
     
  14. halfmile

    halfmile Well-Known Member

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    75 no good for deer.

    Sight the round you will use for 1 & 1/2 high at a hundred, check cold POI, and you're good to 300 yards.

    As previously said, the first shot from a cold bore may (or may not) differ from range shooting a warm barrel. All rifles are different. I have one that shoots the cold shot in the same place as all the rest.

    If you can hit a pie plate you can kill a deer.

    I want some sausage.

    HM
     
  15. sliverbulletexpress

    sliverbulletexpress TS Member

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    slic lee has it right.
     
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