UNKOWN DISTANCE (UKD) RAPID RIFLE ENGAGEMENT, BY JRS

Posted by NC Scout | Aug 3, 2020 | Guest AuthorsWeapons |  |     

Unkown Distance (UKD) Rapid Rifle Engagement, by JRS

This is a basic rifleman’s guide to rapid engagement on targets at unknown distances out to 500(ish) meters.

This approach is modeled on low powered variable optics, using mil based reticles and a 100m zero.

This is not meant as a mil relation article but hopefully you can start to pull the beauty of mils from it.

I will demonstrate the approach with a variety of ammunition.

My acceptable impact area is an IPSC “B/C” zone target.

The dimensions of the of this target are:

60 centimeters tall x 30 centimeters wide OR 23.62 inches wide x 11.8” inches wide

There is a relation, or three “math” things the shooter must grasp and put together to make the shot.

-Target Size, in mils at various ranges

-What is the bullets drop

-What is the target affording me to hastily make a snap call on range

So, lets math this real quick. Below is a mil relation chart showing the height of the target in mils at the various ranges. Understanding your desired area of impact, and its mil relation to range, tells the shooter how much “slop” he can get away with.

RangeSize in mils2752.2
10063002
1254.83251.8
15043501.7
1753.43751.6
20034001.5
2252.74251.4
2502.44501.3

Next we must understand what our round is doing at various ranges. These are all fairly generic rounds coming from a 14.5” rifle with a 100m zero. (This is all generated from Applied Ballistics)

14.5”

1:7 twist

2.5” Sight Height

100m Zero

Round55gr Wolf GoldIMI M855Frontier 75gr BTHPIMI 77gr SMK62gr GDSP
Muzzle Vel30302960261526002589
1000.00.00.00.00.0
1250.00.00.00.00.0
1500.10.10.10.10.1
1750.10.10.30.30.3
2000.20.30.50.50.5
2250.40.40.70.70.8
2500.60.60.90.91.0
2750.90.81.21.21.3
3001.11.11.51.51.6
3251.41.31.81.82.0
3501.71.62.12.12.3
3752.01.82.42.42.7
4002.32.12.72.73.1
4252.72.43.13.13.5
4503.02.73.53.53.9

Now lets compare the above chart, to chart relaying size:

The red highlighted cell indicates where the bullets drop, exceeds the target size. In lay mans terms, this means where you can no longer hold the top edge of the target and achieve a hit.

***Given a 14.5” barrel, a variety of commonly available rounds, and a desired impact area of 24” in height. You can get out to 300-350m just by holding the top edge of target with a 100m zero.***

B/C Zone SizeRound55gr Wolf GoldIMI M855Frontier 75gr BTHPIMI 77gr SMK62gr GDSP
Muzzle Vel30302960261526002589
61000.00.00.00.00.0
4.81250.00.00.00.00.0
41500.10.10.10.10.1
3.41750.10.10.30.30.3
32000.20.30.50.50.5
2.72250.40.40.70.70.8
2.42500.60.60.90.91.0
2.22750.90.81.21.21.3
23001.11.11.51.51.6
1.83251.41.31.81.82.0
1.73501.71.62.12.12.3
1.63752.01.82.42.42.7
1.54002.32.12.72.73.1
1.44252.72.43.13.13.5
1.34503.02.73.53.53.9

Now I am going to introduce hasty range guestimation using mils

There are two sizes to keep in mind. 12 inches and 20 inches.

TgtMil ReadRange(m)TgtMil ReadRange(m)
20”.956412”1.0305
20”150812”.9339
20”1.146212”.8381
20”1.242312”.7435
20”1.339112”.6508
20”1.436312”.5610
20”1.5339

Realistic hasty milling of a target, with most 1-6/1-8/1-10 reticles I can mil targets to +/- .2 mils. Meaning I can tell the difference between 12” that mils at 1.0 and 12” that mils at .8.

***If you are engaging a target that is conducting proper individual movement techniques (3 to 5 seconds rushes) is it reasonable to expect to mil a part of him?***

***This is when it comes down to ammo choice. I personally use 75gr and 77gr loads. So going forward I will use that***

Now the shooter has to look at the relation and make the judgement on:

-Ease of milling the target (1.0ish is easier to read than .6ish)

-Target size (in mils) compared to bullet drop. (What can I hold, and still be inside the target?)

All that boils down to this, for using a 14.5” rifle and shooting 77gr SMK

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Author: Alfred E. Neuman

EDITOR ONLY, 74 year old geek, ultra-conservative patriot.

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