Calculating POI for Leupold Boone and Crockett Reticle

Discussion in 'Long Range Scopes and Other Optics' started by Full Curl, May 28, 2015.

  1. Full Curl

    Full Curl Well-Known Member

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    Hi all. I need some ballistic help from some of you much more knowledgeable and experienced marksmen. I have a custom 7mm rem mag with a Leupold 4.5 x 14 x 40mm VX-III scope with the Boone and Crockett (B&C) reticle. I have been shooting the gun well for a couple years, mostly under 300yds shots on game, but I’d like to try to take this setup to the next level and get comfortable in the 300-500yd or 600yd range.

    At the 300 and 400 yard range using the corresponding hatch marks in the reticle using the large triangle, I am a bit off 6”+. I’m sure some is shooter error but I’d like to take this step by step from the start since the load data in the cartridge Leupold shows doesn’t match what I’m shooting. Closest is the 150gr 3050fps in Group A (large triangle with a 200yd zero).

    Here’s Leupold’s manual for its Ballistic Aiming System…
    http://www.leupold.com/wp-content/uploads/2014/09/BAS_Inst_Manual.pdf

    I’m shooting a 160gr Accubond bullet and I’m using a 200yd zero. I do not know my fps, but I have a chrono on order and will measure that as soon as I get it.

    Once I have my fps and know my bullet’s BC, I’d like to build a POI chart for each of the hatch marks in the reticle based on the scope set at specific power settings.

    I’ve read some old posts on this subject and they reference a tool named “reticle tool” in a program named “Exbals”. I found the program but can no longer purchase it and emails to the company/developer have gone unanswered.

    I’m hoping folks on this site can help walk me through this process of how to determine exact POI/MOA figures for each hatch mark in the reticle for my load at any given power setting.

    Any and all help would be greatly appreciated!! Thank you.
     

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  2. Greyfox

    Greyfox Well-Known Member

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    The easiest was that I was able to establish pretty exacting impacts for each of the hasH marks on my B&C:
    -Zero your rifle at 200 (or 300*) yards using the 200 yard hashmark.
    -Set up a target at 500(or 600*) yards with a sheet of paper 6 feet in height with a aiming point near the top of the target and fire a group(3-5shots) using the 200 yard mark.
    -Mark the fired group which should be near the bottom portion of the paper so it can be seen at 500 yards and adjust your scope power so the 200 yard hash is on the top target spot and the 500 yard hash is on the marked 500 yard group. The intermediate ranges should be very close, but confirm at the actual ranges using the appropriate hash mark distance. Always use this power setting with your load. This approach worked well for me hunting coyotes at all distances to 600 yards with my 270WSM/Leupold VX3 4.5-14x-40 with B&C. 140gr Nosler at 3100FPS.Using this approach you also have the option of firing a group on the 500/600 paper with each hash mark and calculating the drop in MOA for each hashmark. This can then be matched up to a ballistic table to determine the exact range of each hash mark.

    *When using very high velocity loads with the B&C reticle more precise matching of the hash marks(ballistic curve) might be achieved using a 300/600max yard zero instead of 200/500max. This is explained in their literature. Also listed is the MOA drops for the hasH marks for 200 and 300 yard zero settings for ballistic table, yardage matching of the hash marks.
     
  3. Full Curl

    Full Curl Well-Known Member

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    Thanks Greyfox. I’m sure your described method worked well. Did you ever enter your information into a ballistics program to further extrapolate your data? I’d like to try to first run my numbers through some good software to see what the numbers are and then go to the range and see how close they are. I’ve read that both EXBALS BALLISTIC SOFTWARE and NIGHTFORCE BALLISTIC SOFTWARE (maybe the same program?) can generate POI numbers for each hatch mark in the reticle but I can’t find where either EXBALS or NIGHTFORCE SOFTWARE is still available. Has anybody successfully calculated POI numbers for the different hatch marks in the reticle with different loads using software? Are there other available software packages that will do this?
     
  4. Greyfox

    Greyfox Well-Known Member

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    Yes, I have done this successfully, using Shooter which is installed as an app on my I phone. Most any JBM based algorithm/ program like the Nightforce one will give good info if your inputs are solid.
     
  5. Full Curl

    Full Curl Well-Known Member

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    Thanks. I'm not real familiar with ballistic software but as I understand it I need something with an actual "reticle" tool where I can input the actual hatch mark measurements of the scope. I found some old information where EXBALS and NIGHTFORCE both had this feature but both are no longer available. I think some of the scope manufactures have their own software versions but I think they are restricted to only the reticles they offer and I cannot input data for Leupold.
     
  6. sscoyote

    sscoyote Well-Known Member

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    I used to use the reticle zeroing apps in the ballistics programs (Exbal), but I just note the variation from ballistics programs calcs, in MOA (using the reticle subtensions either measured or taken from the catalogs), and readjust mv and sometimes BC to get the best fit possible in the conditions I'm shooting in, put the zeros in a Butler Creek scope cap cover, and test occasionally in the field.

    There is some legitimacy to adjusting the power (and therefore reticle subtension) to easily remembered zeros for faster field applications. I have seen a buddy apply this with his AR-10 243/Leupold Varmint Hunter's reticle to devastating effect on small vital zone targets like predators to ranges of 600 yds. and even further, and have no doubt it would work great for big game.
     
  7. FEENIX

    FEENIX Well-Known Member

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    I have the same scope on one of my .300 WMs and I use Strelok apps in my phone, it's free and it has the B&C reticle in its database.
     
  8. Full Curl

    Full Curl Well-Known Member

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    Thanks Feenix. I never heard of that program before. After checking it out it looks like something that might work. I know that most of the major scope manufactures like Zeiss, Hawke, and Nikon all have their own ballistic reticle calculator software but I don’t know if any of them include reticles other than the ones they offer in their scopes…? Assuming not.

    Do you know if Strelok can be used on a normal desktop PC or if it can only be run as an app on a device?
     
  9. FEENIX

    FEENIX Well-Known Member

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    Yes, for a small fee >>> Strelok | Windows Phone Apps+Games Store (United States)
     
  10. Full Curl

    Full Curl Well-Known Member

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    Thanks Feenix. I'll check it out. Much appreciated.