How To: Ballistics Testing

[Blutze]

INTRODUCTION

I started working on this, ages ago, to counterbalance the "favourite gun" thread (https://www.fuckknows.eu/forums/topic/2768-favourite-gun/) with all its incorrect statements. Turns out that thread kinda faded out while I was away without internet, but it appears you fools still need someone to push you down the path of a scientific approach and actually doing your homework. Well then, let me teach you how to evaluate certain measurable properties of firearms in ArmA 3.

As an example, we will be looking at Bohemia's marksman rifles (modified by ACE3) in 7.62x51 mm NATO:

• SIG 556 (Marksman DLC)
• HK 417 (Apex)
• M14 (Marksman DLC)
• Mk 14 EBR (Vanilla)

We won't actually find out which is the best designated marksman rifle in our entire modset, just which is the best ballistically (and by a few practical attributes as well) between those four. And by that point you will know how to do it yourselves, so you can add all the other options to the list and compare.
 

GATHERING OUR TOOLS

We will be doing all of this on this scenario "Altis Advanced Shooting Range" (http://steamcommunity.com/sharedfiles/filedetails/?id=752850965). It offers not just access to the arsenal and targets at known ranges, but also readings of velocity, precision, accuracy, and damage as well as the option to switch into zeus mode.

On the briefing screen, before loading into the game world proper, we can already enable one of those features by clicking on "5 shot groups" as shown here:

This is also where we can add vests to our targets for a variety of purposes, but we won't do that today and we would have to first equip the vest we want ourselves.

After loading in, we find an arsenal box to the right and the option to turn off recoil (which only includes muzzle climb, some guns still jump around a bit) and sway (this apparently sets sway to what you would have at 0 kg load and full stamina, which is still not completely stable) on the mousewheel menu.

As we are testing full power rifle ammunition including some specialized variants and the regular accuracy targets can actually be destroyed, we will go into zeus mode (just press 'Z') and move the pop-up target from under the umbrella next to the 500 meter targets, at a safe distance from any ragdolling the VR target might do. While we're in zeus, we also delete the BLU player slots before VCOM takes over and has them invade the shooting range.

 

PHILOSOPHY

You need to keep in mind that we are analysing the rifles' performance, not mine. As such, we will do everything we can to take the shooter's skill out of the equation: We are using the highest magnification scope we can get (Schmidt & Bender 25x if you are running the 3cb BAF Weapons <-> ACE compatibility mod as you should, otherwise the Nightforce), go prone, use a bipod, set the mouse to the lowest possible sensitivity, and turn sway off with the aforementioned interface option.

While our main focus will be on ballistic performance, handling characteristics are a part of weapon performance as well and need to be taken into account to find the "best" rifle for a particular purpose. They are rather difficult to measure in a consistent way, so we will just do our best.

 

INTEGRATING REAL LIFE KNOWLEDGE

One of the options we will be looking at is choice of ammunition, and we are greeted with a long list of terms and abbreviations that may or may not mean anything to us.

And before anybody thinks that doesn't matter or anything, have a look at these three:

So what do these terms mean for our experiments? Tracers have no effect on performance in ArmA, IR-DIMs are tracers only visible with nightvision, and subsonic ammo is always substantially weaker than regular stuff. Still leaves us with some others, so let's look at the Wikipedia article for 7.62x51mm NATO (quote slightly condensed and cleaned up):

Quote

Ball, M80: 147-grain (9.5 g) ball cartridge.
Ball, Special, M118: 173-grain (11.2 g) Full Metal Jacket Boat Tail round specifically designed for match purposes. During a period in the early to late 1980s the performance of the round declined. Powder, primer, and brass were the same as standard ball rounds; bullets and powder charges varied in weight due to worn machinery and poor quality control. Since it couldn't be called "Match" due to its erratic trajectory, it was renamed "Speshul Ball".
Ball, Special, M118LR: 175-grain (11.3 g) Match-grade round specifically designed for long-range sniping. It uses a 175-grain (11.3 g) Sierra Match King Hollow Point Boat Tail bullet. The propellant's noticeable muzzle flash and temperature sensitivity led to the development of the MK 316 MOD 0 for Special Operations use.
Special Ball, Long Range, MK 316 MOD 0: A 175-grain (11.3 g) round specifically designed for long-range sniping consisting of Sierra MatchKing Hollow Point Boat Tail projectiles, Federal Cartridge Company match cartridge cases and Gold Medal Match primers.
Ball, Barrier, T762TNB1 MK319 MOD 0: Enhanced performance against targets behind barriers; enhanced terminal ballistics and reduced muzzle flash in short barrel carbines, 130 grains (8.4 g).
Armor Piercing, M993: 126.6 grains (8.2 g) armor-piercing round, black cartridge tip.

In summary: Mk316 and M118LR should be rather similar and very precise, Mk319 and M993 could potentially deal more damage depending on how things are implemented in the game, and non-LR M118 and M80 aren't all that interesting. As the only one that we could exclude based on that is from a different mod author who might be applying different balancing standards, that doesn't really help us drop any - but hey, we had a giggle about Speshul Ball.
 

METHODOLOGY

What we will start with is shooting a single round of the same ammunition from each rifle at one of the pop-up targets behind the TV and compare the impact velocities (make sure you don't overpenetrate into the static guns behind the target). This simply gives us an idea about barrel length as ingame stat so we might be able to rule out shortbarreled contenders, especially for longrange weapons such as these. Conversely, even when comparing CQB options you should keep in mind that short versions being quicker and handier is correlation, not causation - those ingame stats have no effect on each other, it is only the mod authors' good conscience that keeps them in a realistic relation.
 
Next we shoot a total of twenty groups on the 500 meter pop-up target, one for each combination of gun and ammunition. I guess at this point I will have to explain what I mean by "shooting groups", so here is a breakdown:

1. Without adjusting your point of aim or the settings on your aiming aids, fire a number of rounds (usually 5) at a defined point, such as the center of an accuracy target.
2. Out of those shots find the two impacts the furthest apart, and measure their distance to each other.
3. Set that distance in relation to the firing distance in the following geometric construction:

The angle within the tip of that triangle at the muzzle, measured in minutes of angle (as in, sixtieth of a degree), is the value of precision we are measuring with this procedure. On this particular scenario, we can simply use the value displayed on the second to last entry when we shoot our group on one of the accuracy targets:

For ease of calculations, remember that 2.91 centimeters of dispersion per 100 meters of firing distance is a minute of angle. So 5.82cm cm at 200m is the same as 29.1 cm at a klick. And put it into perspective: modern standard issue rifles are expected to have better than 2 MoA precision, subcarbines for CQB might get by with 3-3.5 but can easily be better, marksman rifles should have less than ~0.8, and actual (modern, high end) sniper rifles rarely are above 0.5 minutes. The SVD, from a time when the standard rifleman didn't have any optics and extending the squad's effective range from 300 to 500 meters was a relevant change, comes in at about 2 minutes - enough to hit a man-sized target at 500 meters.

While we have each of the rifles out, we also do the damage testing for all the ammo types. We could change the target's vests, but leaving them alone won't really skew our results as long as they all have the same one; so we just hit the guy center of mass until we see a repeatable number show on some of the torso subzones. Aaaaaaand it turns out some of our ammo breaks the scale at 500 meters, so we switch to 700. Also, because we are S-M-R-T smart, we don't do damage testing on the HK417 - same barrel length, so the damage is gonna be identical to the SIG.

 

RESULTS - PRECISION & DAMAGE

SIG 556: Vanilla ammo sucks (as expected), M118LR is not as precise as the more expensive Mk316, Mk319 is pretty precise for a round designed for more intense combat and anti-material purposes, and both Mk319 and M993 with their rather light projectiles can't really hold up in damage. The change from 500 to 700 also shows that Mk316 loses less velocity from air resistance, to the point of overtaking Mk319. Overall, Mk316 looks like a clear winner (the expensive thing designed for this specific purpose wins, who woulda thunk). Let's see if that trend continues.

HK 417: Yeah no. Its so inconsistent, you can't even get consistently bad results: almost decent groups (1-1.3 minutes), and then you get a flier that turns it into a 2+. We got things to do and places to be, so lets continue with the next one.

M14: Bit of a drop in precision, and the tiniest damage increase. Otherwise the same pattern as the SIG.

EBR: Same pattern again. Its actually more precise than the old one, but it doesn't hold a candle to the SIG, and deals less damage by another sliver.

 

WEAPON HANDLING

The easiest part of this to get actual results is weight. If you want, you can completely strip the character so the load display shows the weight of the actual gun. And if your gun takes mags from different mods, you have to juggle those around as well.

• SIG 556: 4.08 kg
• HK 417: 7.26 kg
• M14: 4.17
• EBR: 5.08

Ooooooh boy what where they smoking on that 417. In fact, all the Apex guns are massively overweight. And why is the weaker, short barreled EBR heavier than the M14? Otherwise, the M14 is a just a tad heavier than the SIG for a longer barrel. Huh.

 

Next, we're gonna look at recoil. Waste a set number of rounds from a magazine (usually 20 for assault rifles, we're gonna go with 15 here), put the rifle on full auto, aim at the bottom of the 25 meter target and let rip without moving your mouse or otherwise compensating. We're interested in how high up on the target our last bullet is. Repeat until you are confident in your results, they absolutely will vary. Oh, and remember to turn recoil and sway back on.

SIG 556: A bit of variation, but it does paint a picture.

HK 417: Same amount of variation, but a tad further up in total. From a heavier gun. Well, serves to show that the two stats aren't mechanically linked.

M14: In some runs, the last round is only brushing the target and ricocheting off into the wild. I guess this is intended to model missing some modern recoil managing mechanics such as an inline barrel and stock, adjustable parts and decent buffers that are missing on this venerable Vietnam veteran.

EBR: Doesn't have a full auto setting. In semi it is controllable enough to just blast away in CQB or not to lose track of your targets at range.

Of course this isn't the most important aspect of a marksman rifle, but certain other gun types absolutely do care about this, and we needed to go through the methodology. Actually... go ahead and do this with the RHS muzzle breaks on AKs. Yeah, those things have no effect at all or at least way less than what could be seen through the variance of this method.

One more thing to keep in mind is that the rate at which stance, weapon rest and bipod affect recoil management isn't standardized. RHS Minimis for instance have next to no muzzle rise prone and on the bipod, while the NIArms variants have a noticable amount left; but firing offhand the RHS guns go all over the place while the NIArms pieces are still kind of controllable. As such we would have to do at least three sets of this test, but ugh. Nah, only gonna do that on machine guns.

 
Number three on this list is inertia, the delay you experience when turning around. We are approaching uncomfortable levels of rough measurements here: Put on a properly implemented collimator sight (the M68, for instance) and push your mouse to the side as fast as you can (and do both directions, they are slightly different). The less the dot moves within the frame, the more agile your gun... And these four are actually close enough together that you can't measure the difference this way. We could try to look up the stat in the code, but that's a totally different rabbit hole.

Attachments such as bipods and lights absolutely affect inertia, while different arrangements can make it impossible to compare apples and apples because of perspective changes:

 
And lastly you have sway (swooshing around while stationary, as from low stamina) which really can't be measured. Have a feel of it, but it won't be conclusive. Just use the lightest option that satisfies your performance requirements; this is probably more affected by the total weight of your gear and your stamina consumption than the gun itself.
 

CONCLUSIONS

What this boils down to is insignificant damage differences, almost insignificant differences in precision between the M14 variants, and a significant jump in precision when switching to the SIG. None of the ammunition types are powerful enough for single-hit kills on the torso at the far end of our envelope. So going from 33 to 20 cm dispersion, which makes headshots or finishing blows on unconscious and therefore prone targets even a possibility in the first place, is a world of difference. Meaning: SIG 556, with Mk316 ammo, is the best option you have on the list we started out with.
 

PARAPHERNALIA

Here, have some competitors from other mods:

• RRA LAR - If your AO doesn't have anything beyond 600, Mk262 out of a 20" barrel deals perfectly adequate damage. The RHS M16A4 is quite a bit lighter and should have the same precision, but refused to do that on camera; and the (silver) BCM Jack is even more precise, but suffers in damage (which is actually the limiting factor here).

• NIArms M14 - 86 damage at a kilometer. Both magazines link to the same ammo, so your rangecard will be stuck on whichever you open it first... but the mags themselves have velocity overrides, so the bullet drop values don't match. Use Mk319 SOST for M14s, and SBLR for G3s (where the mags aren't bugged).

• RHS Mk 11 - This M993 implementation is real fuckin' fast, to the point that it is better than RHS's M118.
• MXM - I thought ACE is a realism mod? But here we are, ramming 48.8mm long cases into chambers made for 39mm caseless ammo. And in case you run into somebody who claims otherwise: 6.5x39 Bohemia is NOT more powerful than the good RHS 5.56 variants. Unless you are pushed into it for M'MMERSION reasons, the only MX series combo you should be using is the MXM with ACE3 6.5 Creedmore.
• PKM - @Mihax209 actually asked once why I recommend AP-I ammo, and I could only remember the conclusions from when I first did the testing, not the specific values. So here it is: The N-list AP ammo is the same as regular ammo, B-list AP ammo deals slightly more damage, AP-I deals the same damage as B-list AP but is faster (less leading on moving targets, less time to dodge, etc).

As a final note: Not everything has the same bullet drop, not every scope has markings in the same place. Good luck finding matching combinations.

 

 

EIGHT MONTHS LATER, AN ADDENDUM

No, ballistic coefficient is not the only thing affecting bullet drop. https://www.twitch.tv/videos/286565606 should demonstrate that pretty well.

Edited December 30, 2018 by Blutze

[Blutze]

@Veagance: you might not remember it, but you asked for this. A lifetime ago.

[Cyico]

I fucking love you.

[Spartan_MiniMe]

This is awesome! Upvotes for you!