Howdy fellow tarkovians!
I'd like to start by giving credit to the creators of this blogpost below for doing all the math and a great job at explaining what's behind this abbreviation:
Being a "visual guy" I wanted to understand how these numbers translate into actually hitting (or missing) my target with certain weapons, so I translated this data into these pics below.
– head diameter is considered 15cm (like in the original post), I used this number to match it visually with a PMC head. (I also measured my head in the mirror just for fun :P)
– the circles are pretty accurate but there was some eye-balling involved, so take it with a grain of salt
– For simplification reasons these deviation circles only take into account the accuracy of the weapon, and NOT the bullet drop. You will have to compensate that by aiming higher the slower your muzzle velocity is. So we're assuming a zero drop.
How to read:
Each colored circle corresponds to a MOA value at that specific distance (100m and 200m). This area will show you what's the possible deviation of your shot from the point you actually aimed at.
For example, firing a 5 MOA weapon at 100m directly at the nose of your target will pretty much guarantee you will hit a headshot (ignoring bullet drop). However, same conditions but aim it at the forehead you will have a chance to miss as part of the circle will be outside of the head area.
Lastly, as a bonus, I've compiled a table with some of the base MOA for the weapons. Do note that MOA depends on the attachments you use on your weapon AND on the bullets you use in it.