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Zeroing a red dot

BAMAAKBAMAAK Senior MemberPosts: 4,484 Senior Member
When I put my C-More on my 15-22, I zeroed it at 20 yds cause that's about what we shoot steel matches at. It is dead nutz accurate, 5 shoot single hole. Today I tried it at 75 yds and it actually shot high. I had to aim below the bottom of and 8 inch steel target to hit it. Didn't matter HV or std velocity but std I aimed maybe an in higher. Once I figured it out, I hit the target over and over but it seems bass ackwards to me, shouldn't .22 be dropping a couple inches at 75 yds?
"He only earns his freedom and his life Who takes them every day by storm."

-- Johann Wolfgang von Goethe, German writer and politician

Replies

  • earlyearly Senior Member Posts: 4,950 Senior Member
    The muzzle points slightly up in relation to sighting line of the sight. Not enough to notice at 20 yards, but plenty at 75.
    My thoughts are generally clear. My typing, not so much.
  • knitepoetknitepoet Senior Member Posts: 21,086 Senior Member
    Think about how much the line of the bore has to be angled up to intersect the line of sight @ 20 yards and you'll understand how you're still high @ 75


    ETA: and it wouldn't matter if it's a red dot or a regular scope, if they're mounted the same height above the bore axis
    Seven Habits of Highly Effective Pirates, Rule #37: There is no “overkill”. There is only “open fire” and “I need to reload”.


  • BAMAAKBAMAAK Senior Member Posts: 4,484 Senior Member
    Well I get all that but the math does not seem to add up to me. Let's say it's 80 yds instead. The sight is about 1.5" above the bore so zeroed at 20, the bore should be aimed about 4.5" high at 80 right? .22 should drop 2-3" or more at that distance so at most I should be aiming 1.5" low, but I was aiming as much as 6" low. What am I missing?
    "He only earns his freedom and his life Who takes them every day by storm."

    -- Johann Wolfgang von Goethe, German writer and politician
  • earlyearly Senior Member Posts: 4,950 Senior Member
    I think the 22lr may have less drop than what you're supposing.
    My thoughts are generally clear. My typing, not so much.
  • bisleybisley Senior Member Posts: 10,798 Senior Member
    Your sight is merely intersecting the downward arc of the bullet, at two points in it's trajectory. Even though the arc is always downward, the muzzle is tilted upward so that your sight line will intersect it. You are dealing with a pivoted arc (trajectory) so that it will intersect your line of sight. So the bullet impact will never be lower than your line of sight until it passes the second intersection point, or before it's first intersection point.
  • Elk creekElk creek Senior Member Posts: 6,450 Senior Member

    This is what he said.....
    Aim higher, or get a bigger gun.
  • shawn1172shawn1172 Senior Member Posts: 588 Senior Member
    I agree with the OP zeroing at 20 since that is the distance he shoots at matches but what distance would be recommended to zero a red dot on more of a general purpose gun to be used st varying distances? How caliber dependant is the answer? I figure most people wouldn't be using a red dot at any more than 100 yards.
  • earlyearly Senior Member Posts: 4,950 Senior Member
    shawn1172 wrote: »
    I agree with the OP zeroing at 20 since that is the distance he shoots at matches but what distance would be recommended to zero a red dot on more of a general purpose gun to be used st varying distances? How caliber dependant is the answer? I figure most people wouldn't be using a red dot at any more than 100 yards.

    I generally zeroe my 22 rifles at 50 yards. A hundred is too far to walk for target shooting and most shots hunting seem to come closer than 50 yards even on the prairie.
    My thoughts are generally clear. My typing, not so much.
  • shotgunshooter3shotgunshooter3 Senior Member Posts: 5,733 Senior Member
    I zero to the Army standard: 3/8" low at 25yds which keeps it on a man sized target to 300 (62gr ammo, 14.5" barrel).


    Sent from my iPhone using Tapatalk
    - I am a rifleman with a poorly chosen screen name. -
    "Slow is smooth, smooth is fast, and speed is the economy of motion" - Scott Jedlinski
  • BAMAAKBAMAAK Senior Member Posts: 4,484 Senior Member
    Well, I need to shoot a stage at side match for next months state match that is progressive from 50 to 150 yds. I don't think that red dot is the answer since I have a 16 MOA dot on it for speed purposes which will probably cover the target at 150yds. I have 1 MOA dot modules for it but I don't want to mess with it the day before the main match. I guess I could scope another 15-22 I have or maybe my marlin. Competition guns are to specialized even though NSSF is not supposed to be that way.

    Have the same problem with pistol but I think that is only out to 60 yds it only has a 12 MOA dot which may be OK.

    Good news is my Grandaughter shot the rifle with the red dot on it for the first time this weekend and she was rocking it. Sub 10 second strings w/o misses which is pretty good for an 8 y/o. She is a good shot with an iron sight rifle but very slow, like 30 seconds or more. She really took to the dot.
    "He only earns his freedom and his life Who takes them every day by storm."

    -- Johann Wolfgang von Goethe, German writer and politician
  • bisleybisley Senior Member Posts: 10,798 Senior Member
    I don't shoot matches and I can't hit small targets at 50 yards with a red dot, or iron sights. So, I zero my plinking/SD AR-15 at 50 yards, with a 62 grain bullet. This yields a POI of -0.6 inch at 25 yards, dead on at 50 yards, +0.3inch at 100 yards, and -0.7 inch at 150 yards...if I do everything perfectly, which I don't. So, theoretically, I would never be as much as 3/4" off target by putting the crosshair on the bulls eye. This is just right, for the way I use this rifle.
  • knitepoetknitepoet Senior Member Posts: 21,086 Senior Member
    BAMAAK wrote: »
    Well I get all that but the math does not seem to add up to me. Let's say it's 80 yds instead. The sight is about 1.5" above the bore so zeroed at 20, the bore should be aimed about 4.5" high at 80 right? .22 should drop 2-3" or more at that distance so at most I should be aiming 1.5" low, but I was aiming as much as 6" low. What am I missing?
    Most ARs have the sight 2-2.5" above the bore which doesn't sound like much of a difference, however it actually makes a huge difference.

    Sighting in at 30-35 yards with a 223 AR will normally zero it at ~250-300 yards as well
    Seven Habits of Highly Effective Pirates, Rule #37: There is no “overkill”. There is only “open fire” and “I need to reload”.


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