Correcting SA ballistics

[-Gews- 7443]

Right now we have a few guns in game. However, without exception, all of them have incorrect ballistics. By this I mean incorrect muzzle velocity, incorrect velocity loss, or both. This is extremely easy to fix. Hopefully the current values are placeholders that will be corrected soon.
 
 
Anyways, here are the guns with wrong ballistics, in order of the seriousness of the errors:
 
1. 12 gauge (IZH-43) half corrected
2. Magnum (Colt Python) corrected
3. FNX 45 corrected
4. SKS half corrected
5. Mosin-Nagant / M4A1 corrected
 
 
 
12 GAUGE
 
First off, the muzzle velocity is 900 m/s. Impossibly high, and the most serious error. (This has been corrected) Second, the airFriction is a generic "0.05" which doesn't correspond to real life. (This has not). This is true for both buckshot and slugs.
 
Velocity vs range, buckshot

 
More appropriate figures for buckshot would be initSpeed 404 m/s with an airFriction of -0.00715. Initspeed is now correct, but pellet airFriction is that of Mosin bullets.
 
Velocity vs range, slug

 
More appropriate figures for slugs would be initSpeed 430 m/s 475m/s with an airFriction of -0.004. Slugs have the correct velocity, airFriction is still the original value but not a huge deal.
 
 
 
.357 MAGNUM
 
Currently, there is no .357 Magnum. I say this because it has the same velocity and airFriction as .45 ACP, so one could very well argue it's not a .357 Magnum, it's just a .45 ACP labeled as one. Not anymore, .357 Magnum is correct.
 
Outdated information, but suggested changes remain the same.
 
Velocity vs range, .357 Magnum

 
More appropriate figures for .357 Magnum would be initSpeed 360 m/s with an airFriction of -0.00166.
 
This is for a Colt Python with a 6-inch barrel firing your average 158-grain ammunition.
 
 
 
.45 ACP
 
They got the muzzle velocity correct, but it loses far too much velocity over range. The current values are taken from ArmA 3, but it produces incorrect ballistics. This is now correct.
 
Velocity vs range, .45 ACP

 
More appropriate figures for .45 ACP would be initSpeed 260 m/s (no change) with an airFriction of -0.00072.
 
This corresponds incredibly well with real-world figures for 230-grain ball out to 150 meters. Note the airFriction seems very low - this is because of the very low muzzle velocity, which airFriction depends upon.


7.62x39

The 7.62x39 has been given a muzzle velocity of 930 m/s from the M59/66A1 (3,050 ft/s), which is far too high (a copy-paste from the 30Rnd_556x45_STANAG magazines in ARMA). As well, it loses too much velocity, the air resistance has been set too high (the value from ARMA produces incorrect results, it was wrong in ARMA as well).

This should have an initSpeed of either 748 or 756 m/s from the 22-inch barrel of the M59/66A1 and an airFriction of about -0.0014.* This provides fairly true-to-life velocities out to 600 meters or further.

 

Since 0.34.XXXX the muzzle velocity has been changed to a more appropriate 730 m/s, however airFriction remains at -0.00195.
 
Edit: since the ammunition in-game is "Calm Bear" hollow point, which is also flat-base rather than boat-tailed (basing on Brown Bear HP) I re-checked these values... and I'd still stick with the same ones. 748 m/s, -0.0014.


 
 
 
7.62x54R
 
The main problem with this one is muzzle velocity. It fires at 930 m/s, which is the M16's muzzle velocity from ArmA 2.
 
Velocity vs range, 7.62x54R

 
More appropriate figures would be an initSpeed of about 860 m/s, and an airFriction of -0.00098. These could both vary somewhat. Edit: -0.00096 might fit slightly better for steel core.

 

This has been corrected.
 
 
5.56x45mm
 
Again, currently it has a wrong muzzle velocity - 930 m/s. It should be 884 m/s with M855 ammunition, or 905 m/s with M855A1.
 
As well, airFriction is slightly too high - it should be lowered to about -0.00129. If memory serves, ArmA 3 has it at -0.0012.
 
I did not make a graph for this one, since the overly high muzzle velocity + overly high airFriction led to a similar overall result as a lower muzzle velocity, but lower airFriction.
 
 This has been corrected (velocity is 884 m/s as per M855 and SS109 from 14.5" barrel)
 
 
 
If you want to verify this, simply create a script that tracks bullets and logs their current velocity and range, then edit some values and fire away. ArmA 2 and 3 use the same ballistics as DayZ, so results in those games should be identical.
 
 
 
 
 
Edit: added proposed ballistics for the Ruger 10/22 and the 7.62x39mm used in the SKS and AKM (no AKM yet, but would be shocked if it didn't eventually make an appearance).
 
 
 
.22 LONG RIFLE
 
This should have an initSpeed of 380 m/s and an airFriction of about -0.00215. This provides a decent agreement to 120 meters for standard velocity 40 grain ammunition.
 
Edit: could also be 320 m/s instead if a suppressor is planned, keeping it subsonic.

 

This has been corrected (380 m/s as per normal .22 LR HV)
 


 
 
Edit: added values for the 5.45x39mm for the upcoming AK-74M.

5.45x39
 
This should have initSpeed 914 m/s** and an airFriction of about -0.00114. The bullet has a more aerodynamic design than the standard 5.56. This works well out to 600 meters.
 
The airFriction value is for 7N6 rather than 7N10 because little to no information is available on the aerodynamics of 7N10, but it is likely very similar (form factor).

 

 

As of yet there is no 5.45x39






*exact muzzle velocity depends on ammunition type and country of origin
**extrapolated from v25
 
 
 
 
9MM LUGER
 
This should have a muzzle velocity of 360 m/s and an airFriction of around -0.00174 when fired from a pistol (124 grain standard European/NATO).
 
However from a submachine gun such as an MP5 this becomes about 400 m/s and and the higher muzzle velocity requires an airFriction of around -0.00223.
 
So slight problem with this round. I'd go with the higher submachine gun airFriction which produces acceptable results up to maybe 75m for pistols as well. One could also split the difference.
 
 No 9x19mm yet
 
 
 
9MM MAKAROV
 
This should have muzzle velocity 315 m/s and an airFriction of around -0.00160 when fired from a Makarov pistol.
 
According to Wikipedia the PP19 Bizon has a muzzle velocity of 320 m/s but with an extra 5.4 inches of barrel that seems suspect. I would expect it to be closer to 340 m/s out of the Bizon. This happens to work just fine without changing the airFriction.

 

No 9x18mm yet




8MM MAUSER
 
Muzzle velocity 785 m/s, airFriction of about -0.00071. This is for 12.8 g FMJ-BT bullets and a Gewehr 98.

 

Possible Gewehr 98 was pictured in early screenshots

Edited March 6, 2014 by Gews

[blitz 64]

Unless, they wanted it that way, to make it seem like we are civilians and not trained soldier. However we can only speculate.

 

 

Watch out I see the 12 gauge getting nerfed LOL

[kaylo 11]

would be nice to see, but i got really mad at your autism awareness profile picture. please change it

[NotRedd 51]

would be nice to see, but i got really mad at your autism awareness profile picture. please change it

 

pretty sure its autistic to have an issue with somebody else's interests.

[slippery gypsy 107]

pretty sure its autistic to have an issue with somebody else's interests.

pretty sure all runners in the special olympics are winners 

[Gator Biggs 22]

Well that went off-topic quick.

[Etherimp 1323]

I approve of science... Game wants to be realistic, it should practice what it preaches.

[-Gews- 7443]

Unless, they wanted it that way, to make it seem like we are civilians and not trained soldier. However we can only speculate.

 

 

Watch out I see the 12 gauge getting nerfed LOL

 

I don't think you've understood the topic. One's level of training has nothing to do with a projectile's muzzle velocity or its behaviour while in flight.

 

As well, this is not recommending any changes in damage or weapon characteristics so it can hardly be called a nerf...

[-Gews- 7443]

would be nice to see, but i got really mad at your autism awareness profile picture. please change it

 

 

 

No

[gibonez 3633]

Any idea if they added wind into the equation now ? or are shots that are hitting left and right just due to the dispersion ?

[Aussie Bogan 350]

WOW, good to see someone questioning the in depth dymaics of the game. :D

 

Your hard work is appreciated have my beans sir ;)

[franzuu 211]

Unless, they wanted it that way, to make it seem like we are civilians and not trained soldier. However we can only speculate.

 

 

Watch out I see the 12 gauge getting nerfed LOL

 

Doesn't matter, civilian or soldier. The bullet and the gun are the same

[-Gews- 7443]

Any idea if they added wind into the equation now ? or are shots that are hitting left and right just due to the dispersion ?

 

AFAIK it is just the dispersion

 

The M4A1 has 100 times the dispersion of an ArmA 2 M16A2, the Mosin has 5 times the dispersion of an ArmA 2 Lee-Enfield.

[tgmoore 31]

I would like to see very realistic ballistic profiles for all DayZ weapons. I did two 6 month tours in Iraq as an Infantryman.

[jBrick 116]

AFAIK it is just the dispersion

 

The M4A1 has 100 times the dispersion of an ArmA 2 M16A2, the Mosin has 5 times the dispersion of an ArmA 2 Lee-Enfield.

 

If they go to reality with round-ball ammunition (like that being fired from buckshot) they should be using Journee's Formula.  And, if they did your ballistic equivalencies and ranges / speed may be off significantly. 

[bassist05 69]

I just want my bullets to go where I aim them. I've been shooting at zombies less than 50 meters away and standing completely still on a roof and watched the bullets fly everywhere. 

[-Gews- 7443]

If they go to reality with round-ball ammunition (like that being fired from buckshot) they should be using Journee's Formula.  And, if they did your ballistic equivalencies and ranges / speed may be off significantly. 

 

I'm aware of how round ball ballistics don't correspond to your normal ballistic coefficients. I used both Don Miller and SAAMI spherical drag tables for 00 buckshot and checked them against each other, they gave very similar results.

 

As for maximum ballistic range, it is always wrong in ArmA due to the simplistic nature of the ballistic system. You have to make ballistics correct over the effective range of the weapon, no one will be making shots with a 7.62 at 3,500 meters, so it is better to have it perform correctly over the first 1,000 meters or so. For buckshot, the first 100-150 meters.

 

Journee says 00 buckshot should go 726 yards but this is irrelevant in ArmA - no one will be hitting at that range with buckshot. Anyways, a real-life tracking of 00 buckshot proved it went just under 625 yards at an angle of 30 degrees with a muzzle velocity of 1,020 ft/s, SAAMI and Miller give 600 yards max range... in this instance, closer than Journee.

[-Gews- 7443]

Yeah, so basically the new .357 Magnum fires its bullets at over 3,050 ft/s... unless you use a speedloader, in which case it's only about 850 ft/s.

class B_357_Single : ChamberedRound {

        initSpeed = 930;

    };

   

class B_357_Six : ChamberedRound {

        initSpeed = 930;

    };

 

 

class M_357_Speedloader : PistolMagazine {

        initSpeed = 260;

    };

Mm hmm. This needs to be fixed ASAP before players start using it en masse, otherwise people will complain about it being "nerfed" if they ever reduce the velocity to the correct levels.

[Zogvarn 118]

So basically the .357 is the new "sniper" assuming dispersion isn't horrible?

 

:facepalm:  

Why did they....? I don't even....

[-Gews- 7443]

So basically the .357 is the new "sniper" assuming dispersion isn't horrible?

 

:facepalm:  

Why did they....? I don't even....

Dispersion is pretty terrible but the bullet will only drop about 1 meter at 350 meters, and it will basically behave like a revolving M16 otherwise.

I hope it's just another placeholder. Right now it only appears to take the speedloaders though, which are too slow (like the FNX that would mean no chambering single rounds).

[Zogvarn 118]

Ah ok then, not as bad as I was thinking then. But still bad enough. Thanks Gews for keeping us updated.

[-Gews- 7443]

So the new SKS is almost ready to go. It shoots 7.62x39mm.

 

However it has the same 930 m/s (3,050 ft/s) muzzle velocity as the M4, the Mosin, and the Magnum, which have all had that value copy-pasted from ARMA's M16s.

 

The M59/66A1 should have a muzzle velocity of 748 to 756 m/s. In addition the ballistics for the round are still incorrect, the same as in ARMA. It loses far too much velocity over range.

 

 

Updated the OP.

[gibonez 3633]

How is it that they screwed up the ballistics so much in dayz ?

 

Really hope this was not intentional.

[- Karma - 75]

Great work Gews!

 

I usually don't crunch the numbers from the code itself, but I could tell the ballistics were definitely off.

 

Like you said, hopefully a lot of the values are placeholders for now.  The game seems to strive for authenticity, so I imagine at some point this will be corrected - but you are right in that the real danger here is too many players "getting used to how it works" when it is incorrect and then complaining once it is working properly.

 

I think posting the raw data here along with your alterations is great, it allows those less educated in ballistics to understand what we're talking about - hopefully the Dev team takes your suggestions.

[Heiduk 265]

I approve of science and caring about the details so almost gave you beans but disapprove of useless charts without scales [1] so I took them back. So what exactly is the velocity difference between a DayZ .45 ACP at 150 meters and a real .45 ACP round, 0.00001 %, 0.1%, 10%, 50%?

 

[1] http://www.edwardtufte.com/tufte/books_vdqi