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.223/5.56 Bullet Drop Question

Discussion in 'Black Rifle Forum' started by Smokin45, Nov 28, 2012.

  1. Smokin45

    Smokin45

    500
    68
    Oct 15, 2012
    Dirty Duval, FL
    If I had my gun sighted in at 50 yds, where would the POI be on a target at say 100 yds? 150, 200 etc??
     
  2. WoodenPlank

    WoodenPlank Who?

    7,958
    3
    May 15, 2010
    NW Florida
    Depends a bit on barrel length, but you will be about 1-1.5" high at 100, 2"-2.5" or so at 150, and back to zero around 200-220y.
     


  3. Smokin45

    Smokin45

    500
    68
    Oct 15, 2012
    Dirty Duval, FL
    Sweet thanks man. I see youre in my neck of the woods, Navarre here :wavey:
     
  4. WoodenPlank

    WoodenPlank Who?

    7,958
    3
    May 15, 2010
    NW Florida
    I lived in Navarre when I first moved to Florida. I'm about 35 miles east now.

    If you don't mind the drive, check out Bullets and Bones in Defuniak Springs. They have a VERY nice 300 yard range, and it would make one heck of a place to check out the holds/offsets at different distances for yourself. Depending on your individual barrel, mount, optic and ammo, it can vary slightly. The only way to know for sure is to try it.
     
    Last edited: Nov 28, 2012
  5. Smokin45

    Smokin45

    500
    68
    Oct 15, 2012
    Dirty Duval, FL
    Nice man yeah I love Navarre...

    Ive heard good things about B&B, just a bit too far of a drive for me.. I usually go to ERSC or Styx.. Have you checked out gulfcoastgunforum.com yet? It is a site for people in our area to talk about, buy, sell and trade guns/accessories..
     
    Last edited: Nov 28, 2012
  6. Matthew Courtney

    Matthew Courtney Instructor #298

    3,644
    4
    Oct 14, 2002
    Lake Charles
    Plank's figures assume about a 2.6 inch sight/optic height over bore, which is an absolute co-witness with an f marked FSB. An extra high or low mount will skew the numbers. Take that thing out and shoot it! That is the best way to find out what your gun does with your ammo. Everything else is just a hypothesis.
     
  7. WoodenPlank

    WoodenPlank Who?

    7,958
    3
    May 15, 2010
    NW Florida
    I'm running an LT-129 lower 1/3rd cowitness mount, and those numbers are still pretty damn close for me. The 4MOA dot in the Aimpoint makes it hard to tell for sure, though. Honestly, even with a 1 MOA dot, you're gonna be hitting inside or almost in the dot at those distances.

    OP, B&B is worth the drive, even if only on a rare basis. I was driving all the way to Jay's in Baker to shoot and paying just as much - AFTER paying for a membership there, and twice the drive.
     
  8. WinterWizard

    WinterWizard

    1,417
    5
    Jan 17, 2012
    This.

    I have a 16" barrel also zeroed for 50 yards. I am about 2" high at 100, about dead-on again at 200 (maybe 0.5" high) and about 4" low at 300. That is with 55gr ammo at about 3100 fps out of my 16" barrel.

    This is why I like a 50 yard zero. 0-300 yards and you are never more than a few inches off in elevation. At 50 and 200 POA = POI. At 100 I use a 6 o'clock POA, and at 300 I use a 12 o'clock POA, and I am near the bullseye every time. Simple.

    The AR.15 ammo oracle also has charts for bullet drop and trajectory for different zeroes, etc...

    http://www.razoreye.net/mirror/ammo-oracle/AR15_com_Ammo_Oracle_Mirror.htm
     
    Last edited: Nov 28, 2012
  9. Matthew Courtney

    Matthew Courtney Instructor #298

    3,644
    4
    Oct 14, 2002
    Lake Charles
    Lower 1/3 co-witness is about 2.77 inches over bore, so it's still very close. It is the guys using 1/2 inch risers or mounting onto carry handles who get trajectories that differ significantly.

    On a related note, some of the research BTG has done tends to show that different engraving patterns from different rifling may affect the true BC's of bullets in flight. As interesting as that is, doing the actual testing and measuring to calculate BC for bullets is tedious, grueling work. When the trigger puller shoots the chrono at 300 yards, we have to line everything up all over again.
     
  10. Big Bird

    Big Bird NRA Life Member

    9,695
    1,145
    Aug 7, 2003
    Louisville KY
    Ballistic Coefficient is a nearly meaningless factor inside of 300 yards for most spire pointed bullets. Compare the differences in bullet drop between a low BC bullet and a high BC bullet at similar velocities and you will see fractions of an inch difference in POI in terms of vertical impact between the loads out to 300 yards. Also, BC isn't a constant. Its a mathematical factor which also is a function of velocity.