ARMA and DayZ have always been known for relatively realistic combat and ballistics.
Unfortunately, thanks to recent changes, DayZ no longer has any form of 'realistic' ballistic values. This needs to be fixed.

  I noticed some weird values in the projectile config and going through, I realized that DayZ's realistic ballistics have been changed into complete nonsense! Here are some examples:

1. Shotgun pellets have a muzzle velocity of 350 metres per second, but even if you point the gun high up in the air, the pellets hit the ground after only 75 m due to crazy airFriction SIX TIMES higher than realistic. 
2. The 7.62x54R has an airFriction that is over SEVEN TIMES higher than the .308 Winchester. 
3. The 7.62x39 has an airFriction that is over SIX TIMES higher than the 5.45x39.
4. The 9x19mm has an airFriction that is over DOUBLE that of the .22 LR.
All of these are brand new values, so it's not like they changed the .308 and left the 7.62x54R alone, and that's the reason for the difference. Nope, both were changed but one was given seven times higher airFriction. Those are just some of the most obvious examples. Almost every single round has incorrect ballistics. What makes this more annoying is that they already had decent values. Way back in patch 0.34 they fixed many of the incorrect placeholder ballistics. It seems with patch 0.63 they've gone and unfixed them!

To be fair, I don't know if they've changed how this part of the engine works. That being said, there is no engine in which you give a 7.62x54R SEVEN TIMES higher airFriction than a .308 Winchester. The shotgun pellets DO ONLY GO ABOUT 75 METRES, which roughly matching my calculations that are based on how the game worked before. So I'm going to make the assumption that the ballistics works more or less the same, and that whoever put these new values in made some big mistakes. [EDIT] Did testing, confirmed airFriction works the same as it always has. Suspicion was correct. See reply below.


Based on the above assumption, here are three crazy facts about 0.63 ballistics:

Fact 1. At 2,000 metres the .308 Winchester would still carry half its energy. In real life it loses half by 350 m!

Fact 2.  Buckshot pellets would lose half their energy after travelling 3-4 body lengths (only 6 to 7 metres). 


Fact 3. At 1,000 metres the 5.56x45 would have over FOUR TIMES the energy of the much larger and more powerful 7.62x54R.



To show how bad the changes are, here's a graph which compares predictions for the 5.56x45 in 0.62, the 5.56x45 in real life... and the 5.56 in DayZ 0.63.



I have no idea how they came up with these values, most of which are pretty specific. For example, .357 Magnum at -0.000599. Wow, -0.000599 instead of simply -0.0006. We're talking a small percent of one percent of difference there.

I can tell the devs did some research for the initial muzzle velocities and weights, but not always thoroughly. For example, the 5.45x39 has been given initSpeed/typicalSpeed of 880. Well, that's the nominal velocity out at 25 metres from a test barrel. Someone looked that up, either Google or checking ARMA 3. But the bullet starts at the muzzle, not at 25 metres, and from the weapon's muzzle it should be 900 or more. 



Here are some values I came up with, which are fairly realistic.
Some of these could be further fine-tuned, and I will add missing rounds like 9x39 later.
 
  SUGGESTED VALUES
Ammo type, initspeed/typicalspeed, airFriction 12 gauge 00 buckshot, 404, -0.008
12 gauge slug (Brenneke), 415, -0.005 
5.45x39, 900, -0.00117 (for 7N10)
5.45x39, 900, -0.00125 (for 7N6)
5.56 NATO, 940, -0.00124 (for SS109)
.308 Win, 853, -0.00101
7.62x54R, 845*, -0.00096
7.62x39, 730✝, -0.00144
9x19mm, 360, -0.0023
.45 ACP, 260, -0.0008
.22 LR, 380, -0.0025
.357 Magnum, 445**, -0.0026 *average of Mosin/SVD
**compromise value of revolver/carbine
✝compromise of various weapons
      Feedback tracker: https://feedback.bistudio.com/T133383
Related thread from 2014: https://forums.dayz.com/topic/157148-correcting-sa-ballistics/