Gunslingin’ #3


For this installment, I am going to talk about data. Now, I am not, nor ever claimed to be, one of the Sniper types. I am sure by the end of this some Sniper Steve will be sitting around going “Actually…” which is fine. This is a short version of how I obtained and confirmed data over the year. In that, some things that were never important to me over tens of thousands of rounds suddenly became important.  Applying these things will forever keep you out of arguments about zero distance and other shenanigans of the sort. I used the Applied Ballistics and BallisticARC apps.


Applied Ballistics App

First thing you will need to know is Scope height. For most apps, it is centerline of the scope to centerline of the bore. Your mount height matters for more than clearing lasers. For my Knight’s Armament Company SR15 LPR with a Knight’s 1.5” mount my Scope height measured at 2.8” Now, those that run different height mounts your scope height will change. Measure it. It matters. We have heard Steve Fisher saying 50 isn’t 200 when it comes to zeroing. This is the first piece of data that skews the rule of thumb, always do it this way zeros.


Next, you will need to know information on your scope. You will need to know at a minimum low and high magnification, focal plane, and if the adjustments are in mils or MOA. Most apps ask for a reticle type which is convenient later but not a show stopper. Finding your or a close version of your reticle is nice later when you are doing planning or building a range card. While on reticles, choosing a reticle should be based off planned use and skill set. I use Tremor 3 reticles because of the wind dots. If you are familiar with calling wind in mils vs MPH this may not be the reticle for you. For those of you using anything above 4x magnification with a reticle that doesn’t have some sort of tree for use in wind like the ACOG reticle, wind is going to punish you for your choice as soon as you go to distance. Speaking of zeroing, you will have to choose your zero distance. This is based off how you intend on using your scope and the reticle itself. I zero at 100 with my ATACR but zero at 200 with my Leupold Mk6.


Applied Ballistics App

Here is the hard part. You need to have your muzzle velocity and ballistic coefficient. This is also the next piece that kills the 50/200 zero theory. You can not use the velocity printed on the box. You must put it on the chronograph and get a velocity. Once you have this, you can put this and the other info such as weight into your ballistic calculator. While you are on the Chrono, you need to get your Standard Deviation (SD) from your chosen ammunition. This is the difference in velocity across the sample. High SD’s mean you ammunition is inconsistent. 30-50 Feet per second is a miss at distance.








Now, you can finally acquire a shooting solution for a target at distance. Old timers would have a chart printed out with ranges and drop for that range. For competition, these are not recommended. Shooting a 2-3 MOA target at distance requires accuracy. That’s not just shooting good, that’s the difference between a 3.7 mil hold and a 3.5 mil hold. In conditions such as combat, it may be enough but its still not recommended.

All this must be worked out before you can get on to the next step in the Shot Process which is aiming. In the last blog I talked about stability. Not only do you need to be shooting within a 1.5MOA group, you need to be able to hold on an exact mil. If you are dialing your turrets, you need to be able to hold the center of the reticle on the center of the target. If you have done the work and collected good data, your bullet will go exactly where it was predicted to go on the calculator.


Applied Ballistics App



I will close by talking a little about “truing” your data. For a proper True, you need to confirm your data at the range your bullet goes transonic. This is not always possible, so I highly suggest that you confirm all your data at as many ranges as possible. While doing this Dial your turret and shoot the best groups you can. Remember, you are collecting data for your calculator. You will be able to go in and adjust variables to get an exact prediction of the bullets flight. Once you do, trust your data. I failed to do this in my first match and my data was slightly skewed. My performance plummeted once I lost confidence in the data. We made corrections during the match and I began hitting targets again. I do not recommend duplicating my mistakes.

-Ash Hess


This post currently has one response

  • This is a comment from Ryan Hey of Magnetospeed. Wanted to make sure everyone saw it

    “SD: standard deviation is not the difference across the sample. ES (or “range” in true mathematical terms) is the difference between high point and low point.

    The SD is the deviation from the Average MV in the string or sample. A low standard deviation indicates that the data points tend to be close to the mean (or average MV)

    On truing: you need to true both BC and MV. Rarely are advertised factory ammo MVs correct. Rarely are advertised BCs on boxes of bullets correct. Most match shooters will true Vo (velocity) out to transonic and then true BC past that. This is dependent on caliber/cartridge.”

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