ballistic help

Discussion in 'General Discussion' started by screech, Mar 4, 2007.

  1. screech

    screech Well-Known Member

    Messages:
    1,193
    Joined:
    Nov 26, 2005
    Hello, I got a problem. I was just trying to get a rough drop chart to get so I dont have to use so many bullets creating a real drop chart. I live at about 2500ft. It was about 40degrees and I was shooting a 7mmstw with an 162gr. amax. I was zerod at 100. At 415 it had dropped 17clicks 4.25moa, then at 1100 it dropped about 106clicks 26.5moa. If any of that is wrong please tell me. can some one email me chart to get me close for drops. I dont know exactly how fast they are either. If anyone could help I would be appreciative.
     
  2. Sendero_Man

    Sendero_Man <strong>SPONSOR</strong>

    Messages:
    1,706
    Joined:
    Feb 4, 2007
    what velocity ? what sight above bore height ?

    Or can you tell me what your load is, so we can get close to the velocity ?

    let me know and I'll shoot ya a drop chart.... /ubbthreads/images/graemlins/grin.gif
     

  3. screech

    screech Well-Known Member

    Messages:
    1,193
    Joined:
    Nov 26, 2005
    what the reloading manual said is that i should be getting around 32-3250 I believe. dont have it with me. I dont know on sight above bore height either. it has nightforce rings and bases 56mm objective. How do you measure that? thanks
     
  4. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

    Messages:
    6,848
    Joined:
    Jun 12, 2004
    Most conventional factory receivers are 1.350" in diameter, roughly.

    Then measure your base thickness and the distance from the top of the base to the bottom of the scope tube.

    THen if your using a scope with a 1" tube add 1/2" to this, if your using a 30 mil scope add 0.591".

    So you have 1/2 the receiver diameter+base height+ring height+1/2 scope main tube diameter.

    That will get you your measurement for height above the bore.

    TO be honest, if you use 1.5" for most conventional scopes mounted in the proper location and 1.7" for the big 56mm objectives, you will be extremely close in most cases.

    If you are using published load data, I would say there is a good chance your no where near 3200-3250 fps. YOu really need to shoot your load over a chrono so you know for sure. This is really critical for accurate shot predicting at long range.

    Kirby Allen(50)
     
  5. CAM

    CAM Well-Known Member

    Messages:
    385
    Joined:
    Jan 2, 2002
    screech
    as everyone else said it would just be a guess!!
    you ask for a rough drop

    7mm STW 162gr A-max BC 0.625

    3200 fps zero at 100yds

    scope 1.5 altitude 2500 40 deg

    range MOA
    100 0
    200 2.2
    300 4.9
    400 4.65
    500 6.76
    600 9.06
    700 11.54
    800 14.23
    900 17.14
    1000 20.29
    1100 23.70
    1200 27.41

    Exbal calculator

    CAM

    Edit to add
    to be zero at 100 and drop 26.5 MOA at 1100
    using all the above info your speed is 3050 FPS
    and your 400 yard would be 5.25 MOA
     
  6. screech

    screech Well-Known Member

    Messages:
    1,193
    Joined:
    Nov 26, 2005
    Thanks cam. I used an online ballistic calculator and couldn't get it to hit accurately on 415 and 1100 either. I know that is what I had to come up to hit but it dosent work for some reason. I tried changing velocity, elevation, bc and couldn't get it.

    Thanks Kirby, I dont know why I didn't think of that. I will try and run it over a chrony and see what it says when I have time.
     
  7. screech

    screech Well-Known Member

    Messages:
    1,193
    Joined:
    Nov 26, 2005
    hey cam, what ever you used can you do it again but give it to me in every 25yrd increments. I think you about hit it on top of the head. thanks
     
  8. Sendero_Man

    Sendero_Man <strong>SPONSOR</strong>

    Messages:
    1,706
    Joined:
    Feb 4, 2007
    Sent one to your email, I hope you have excel...
    based off 3050 fps

    (yd) MOA
    0 0.00
    25 3.00
    50 0.50
    75 0.00
    100 0.00
    125 0.25
    150 0.50
    175 0.75
    200 1.25
    225 1.75
    250 2.25
    275 2.50
    300 3.00
    325 3.75
    350 4.25
    375 4.75
    400 5.25
    425 5.75
    450 6.50
    475 7.00
    500 7.50
    525 8.25
    550 8.75
    575 9.50
    600 10.25
    625 10.75
    650 11.50
    675 12.25
    700 13.00
    725 13.75
    750 14.25
    775 15.00
    800 16.00
    825 16.75
    850 17.50
    875 18.25
    900 19.25
    925 20.00
    950 20.75
    975 21.75
    1000 22.75


    SMan
     
  9. Sendero_Man

    Sendero_Man <strong>SPONSOR</strong>

    Messages:
    1,706
    Joined:
    Feb 4, 2007
    2nd table sent....

    Good luck
     
  10. screech

    screech Well-Known Member

    Messages:
    1,193
    Joined:
    Nov 26, 2005
    thanks mucho much
     
  11. Sendero_Man

    Sendero_Man <strong>SPONSOR</strong>

    Messages:
    1,706
    Joined:
    Feb 4, 2007
    let me know how it works for ya...
     
  12. screech

    screech Well-Known Member

    Messages:
    1,193
    Joined:
    Nov 26, 2005
    whenever I get off work early enough I will. Go to school, go to work go to bed and restart cycle is my life and play is when I have time. Got to work this weekend so hopefully next week sometime. What program do you have? thanks again