Collecting DOPE data questions

Collecting DOPE data questions

This is a discussion on Collecting DOPE data questions within the Cartridges & Calibers forums, part of the Sniping Related category; I am trying to collect data of bullet drop at several known distances and then with the help of ballistic programs, find the best approximation ...

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    Member Toni's Avatar
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    Collecting DOPE data questions

    I am trying to collect data of bullet drop at several known distances and then with the help of ballistic programs, find the best approximation of the true bullet path. But things get complicated because I do not have a chronograph so I have to shoot, measure the vertical distance to POA and correct cliks until bullet hits the center. So far, I have collected data up to 400m. I wondered if the collected data would not work if I did not know the Density altitude at the time and location where the data were collected?

    Is this gadget what I need to calculate density altitude or it isn't calculating the station pressure?
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    Senior Member gpark09's Avatar
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    No, it would not work from the beginning. You need a reliable chronograph first to begin with, then worry about the environmental factor.

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    Senior Member mamalukino's Avatar
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    Here is a method I use and it works at consistent altitude.
    On a target I have a leveled vertical line with 4 dots , one at the bottom of the line is the POA, the other three are the POI of a known bullet load at their point POI when dialed for 3, 5 and 600 yards. The target is set at exactly 100 yards.
    I will zero the scope to the new/evaluation load and shoot the zero POA target to verify zero. I will then dial turrets and adjust to impact all 3 other dots aiming at the bottom zero dot.
    These will give me the comeups for the new load.
    I then back the info into a couple of ballistic calculators for my MV.
    The information gleaned from this has allowed me to shoot out to 900 yards accurately with my .308 and 600 yards with my .223
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    Senior Member Skypilot's Avatar
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    I have placed a calculation on my iphone for my DA. Many have barometers as do watches and if not there is enough info around to get a location altitude to get started.

    I also have a chrono, however my ballistic calc will true the dope based on real world drop by adjusting the MV.

    Learn how to hand calc DA from PA based on your altitude/elevation. Then stick that calc on your phone for convenience when leisurely collecting your dope or shooting at a new elevation.
    Last edited by Skypilot; 12-17-2016 at 03:28 PM.
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    Before we had an easy way to measure air pressure and temperature in the field the idea of gathering DOPE came to be ( Data On Previous Engagements ). The idea is you have an idea of the altitude you're at and the approximate temperature. Shoot at several known distances and dial the scope to get the bullet to impact where you're aiming. Write down the "come up" for that distance at those conditions. Repeat for various condition, ( i.e. altitude, temperature ).

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    Senior Member Skypilot's Avatar
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    When you hand calculate you should easily be able to get good/accurate data for calcs except for dew point however you can use METAR to get that from the closest ICAO airport near your location and extrapolate from there.

    You can figure 1" drop in "inHg" per 1000 ft. of increase in altitude ASL
    You can figure a drop in temperature of 3.5 F per 1000 ft of altitude ASL.

    Even without dewpoint, you will likely be within 200-400 ft of true, exact DA
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    Member Toni's Avatar
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    Thank you guys for the input, I'm a bit confused, I would like to know the comeups up to 500 m for the precision hunter eld-x (factory ammo) in my rifle, also be able to calculate corrections of my DOPE for when I go on a hunting trip in different places, conditions, altitude...how can I get it?

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    You must start with muzzle velocity, stir in a bit of Ballistic Coefficient, a pinch of gun measurements, a dash of expected atmospheric conditions, and go visit J.B.M Ballistics.

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    Senior Member gpark09's Avatar
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    Quote Originally Posted by Toni View Post
    Thank you guys for the input, I'm a bit confused, I would like to know the comeups up to 500 m for the precision hunter eld-x (factory ammo) in my rifle, also be able to calculate corrections of my DOPE for when I go on a hunting trip in different places, conditions, altitude...how can I get it?
    Very simple solution for you. Get MagnetoSpeed V3 to get true MV on your OWN rifle, one listed on the boxes will be different than your OWN rifle. If the the price is concern they also have Sporter model with lower price. You can also look into one of those Chrony models with lower price range. Whatever you get, you do need YOUR OWN MV. Then, I would get a Kestrel to instant firing solution or you can pre-run one of those ballistic program, JBL for instance, and input all the different environmental conditions and print them out for the record.

    Don't want to spend any money? Just apply what the box says they will get you to APPROXIMATED figures.

  10. #10
    Senior Member Skypilot's Avatar
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    If you have an idea of the conditions when you shot that day(s) that you got your dope, you can calculate the DA for that previous time.

    If it was done on 3 or 4 different days, it will be difficult to calculate accurate DA for your dope although conditions may not have changed drastically. Only you know would know that.

    If I was attempting to calculate dope from your situation, I'd either start over or use the best estimstion of temperature, humidity, pressure, etc. on the day(s) I shot, then plug in my environmentals into the web ballistic calc, then my factory ammo into a web calculator like JBM( one with a bullet load library) that gives an approximate MV then input my real world drops which would then auto adjust velocities to match that drop(truing your dope)at the environmental conditions you input.

    Then, depending on area you hunt, just change only the DA calculation part of the ballistic program at 1000 ft or 5000' feet intervals depending on where and how hiigh you plan to shoot/hunt. That will give you DA corrected dope for your gun/ammo combo.

    If you climb to an altitude where your eyesight is affected (floaters, corneal swelling) don't go higher without donning your MTOS. Lol
    Defend the poor and fatherless: do justice to the afflicted and needy. Deliver the poor and needy: rid them out of the hand of the wicked. Psalms 82:3-4

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