Data Books for repeatable accuracy – YES even for Varmint hunters

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8654USMCRet

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The Marine Corps teaches its shooters, that is ALL Marines in either boot camp (for enlisted) or Officer Candidate School (for officers) to use data books to record shots, weather conditions, the elevation and windage used at the various yard lines so that their shots are repeatable. Further, as Marines attend annual requalification, they use these same data books.

Many may have the opinion that keeping data books for shooting, especially something like varmint hunting is not required nor desired. I suggest that keeping data of ALL shots taken are not just a good idea but in fact necessary if the shooter wants those hits to be repeatable. Likewise, if it was a miss – provide the necessary information so the shooter can correct the shot the next day or perhaps the next season.

I will use my .223 Remington data in this proposal. Further I’ll cite data from a load that I shoot; the Hornady 53gr Vmax. The load data follows.
  • Powder and amount: 24.0gr H335
  • Shell: Federal
  • Velocity and SD: 3072 FPS / 11 FPS
  • Weather condition for the chrono data: 500ft AGL/52 F/40% RH/Baro 29.80/ 25 Feb 2024
  • Primer used: CCI 400
In this example, I’ll be shooting with a 100 yard zero. For argument’s sake, the target is at 300 yards. The ballistic program I use says that for this distance, for 300 yards, a flat shot (zero degrees angle) required 3.9 MOA of elevation. I took the shot and hit the animal. Perfect shot in the head.

The next season I came to this same area but the exact same shooting position wasn’t available. I had to go up a nearby ridge and take the shot from about 500 feet higher in elevation. Additionally, a warm front comes in and it’s now 52 degrees (as opposed to the unseasonably cool 22 degrees from the previous year). I take the shot and hit well above the animal and it scurries off. I’m frustrated because of the effort that it took to get into this new position. My shot felt perfect. I slowly squeezed the trigger. I took the wind into account. But still I missed. I even used the exact same ammo (reloads from last year). But still I missed and I’m pretty mad at myself trying to figure out what happened?

We know the ballistics from the ammo is good. The gun was in proper working order. The shooter applied the basics of shooting (Breathe, Relax, Aim, Stop, Squeeze). The shot felt great. Let’s also review the differences in the two hunting trips:

LAST YEAR THIS YEAR

Range to tgt 300 yds 300 yds

Elevation used UP 3.9 MOA UP 3.9 MOA

Wind ZERO wind ZERO wind

Temp 22 degrees 52 degrees

Angle to tgt 0 degrees (flat) downhill ?


How could a data book have helped this shooter?

We see that the distance to the target was the same. The shooter used the same elevation because the target distance was the same. We also see there was no wind on either day. The temperatures were different.

So what happened? First, let’s take a look at the shooter to target angle. In this case, we see the shooter in the first year did a ZERO angle (or flat) shot. In the second year, the shooter shot from an elevated location; 500 feet higher than the animal. Because of this angle, the shooter shot well above his prey. Had the shooter recorded the data of his previous year’s shot – he might have realized the difference in elevation, e.g., the angle to his prey created due to this elevation change. The Marine Corps calls this angle data the shooters’ slope dope – but it’s simple the angle to the target. The wind was ZERO on both years, so in this case, the wind had no impact.

I propose that shooters (of any discipline) record the below information. Whether or not you call it your data book is immaterial. The point is to record the data.
  • Date
  • Time
  • Weather conditions (temp, altitude, humidity, Barometric pressure, light conditions, clouds, winds direction and speed)
  • Geographic location (LAT/LONG or Military grid location). Source doesn’t matter as long as the location is accurately recorded
  • Ammo used
  • Rifle used
  • MOA (elevation and windage) used
  • Target angle (shooter to target)
  • Notes on what occurred on that shooting event – good and bad.
This illustration was created to show that had the shooter recorded his shooting information for the first year’s shot, the second year’s shot might have turned out differently. There are numerous examples of data books available online, however, given the proliferation of computers and availability of printers, they are easily made at home. I make my own in MS Word. Other shooters can easily make their own data books that fit their particular shooting discipline, e.g., short range target, long range precision rifle, 3 gun matches, NRA sanctioned, etc., etc.

I hope this short example illustrates how recording shooting data can help the shooter – to achieve repeatable consistency in their shooting endeavors. Again, it doesn’t matter if we call them data books – the main point is to record your shooting information so that your successes are repeatable and your mistakes aren’t repeated.

Good luck in your shooting ands stay safe!
 
Yes and they're numbered so we don't lose them....but they can only number them 1 through 10 because we have trouble with big numbers...😅

Semper Fi
 
LoL.....yes ballistic apps are great. I have one on my Garmin watch, one on my iPhone, and my iPad. How'd we ever get along without them
 
If I miss, I know why I miss, lol.

Guess this would work for Western hunters or Mountain hunters. I couldn’t find 500ft in elevation unless I rented a helo. My only dope is wind direction on certain parts of the property. Just terrain differences throw forecasted winds out the window.
 
The point is, elevation, temperature, winds, humidity and pressure all have a play in accuracy. If not taken into account, they can effect accuracy. Like the internal ballistics of ammunition, if these conditions aren't recorded, the shooter may not be able to repeat the shots.

At the end of the day, the conditions we shoot in, the ammunition we use and the locational data all need to be recorded so that they might be repeatable.

Happy shooting!
 
The Army had some of them thangs back in the late 50's too, but they didn't give us none o' them crayons, though, dang it.🥲 ;)
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in this case, the problem isnt so much the elevation (above seal level) of the shot - its the change of *ANGLE* of the shot. yes seal level elevation will play some role, but thats not likely the problem with your example. or the most significant issue with your example of why you missed.
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using the following diagram for reference - "B" is your target, "A" is you this year & "C" is your shootin position from last year.

you entered dope for the line of sight distance "c", not the distance horizontally to the target "a". so you were dialed for dope much further than the actual shot.

you were shooting from "A" this year, "C" last year. the problem is you assumed "c" from this year was the same as "a" from last year, when in fact it is/was not.

you needed to apply dope for this years "a" measurement. not last years "a" measurement.

Knowing "A", "C", "c" & "b" you could have solved for that - dang trig coming back to haunt us - or allowed a ballistics calc to do it, or used a rangefinder with angle calculation correction to solve it for you.

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I keep a Journal and write down every thing i kill and trap, but I have never needed to keep a book on my shots or how i made them or how far the shot was, it's so flat here you can stand on a brick and see the Gulf of Mexico, the habitat is so heavy there's not a lot of places you can see a predator over 200 yards conditions don't change much inside of 200 yards i don't record my shots unless it's something unusual Murl B.
 
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