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Bullet drop issue of RCO scope(BLUfor) and ARCO scope(OPfor).
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The RCO scope and ARCO scope in Arma 3 had incorrect bullet drop.

Based on real life, the (ACOG/Marks 4/RCO)scope was mainly form by a middle point(Arrow,Dots,or st similar), and a vertical line + 7 short horziontal line(3 of the line have a number on its right)

So the small horizontal line with a number on the rights shows the range for aiming.

EX: a target's at 400m, you will use the horizontal line that have a number 4 on the rights, and aim on the target.

Here is the problems, the bullet drop aren't fit, especially RCO sights.
Using the RCO sights, when the target is at 400m, and using the line "4" to aim and shot the target,the bullets drop higher and hit around 415-430m.

RCO sights: 300m-700m(incorrect)[Issue: the Bullet drop higher[10m-30m)
ARCO sights:600-900m(incorrect)[Issue: the Bullet drop lower[5-15m])

Free to test it and report on this thread.
Using both tracer and normal mags for precise data[because the lights that
6.5 x 39 tracer made disappear when the range reach 500m

Make sure you and your targets are at the same elevation
(Bullet drop are able to affected by the elevation!)


Legacy ID
Have Not Tried

Event Timeline

frostshazzy edited Additional Information. (Show Details)
frostshazzy set Category to Scripting.
frostshazzy set Reproducibility to Have Not Tried.
frostshazzy set Severity to Minor.
frostshazzy set Resolution to Open.
frostshazzy set Legacy ID to 3645413887.May 7 2016, 1:23 PM
DDSSTT added a subscriber: DDSSTT.May 7 2016, 1:23 PM
DDSSTT added a comment.Apr 3 2013, 6:58 AM

Having a slight deviation is normal in fixed optics, bullet drop recital like the RCO are approximate for an average military grade ball ammunition. It is common even today using an ACOG to see bullet drop 5-15m off at +400m. Humidity, barometric pressure, elevation, rotation of the earth also come into factor. Also, a weapon zeroed to one type of ammunition and adding a silencer will increase bullet climb. An M4 zeroed to 300m with Ball ammo will shoot approx. 3-5" higher with a silencer over Zero because of higher muzzle velocity. Silencers are not modeled correctly in Arma 3 nor are the the bullet drops the same for the 6.5mm and 7.62mm. I have not even gone into the bullet type characteristics - Boat-tail or Flat Back bullet, Tracer vs Ball... There thousand different scenarios that could play out here, and there are several other reports covering all this already.

Unable to reproduce in actuall DEV revision 0.53.103608
Try to set up targets at the airport, lay and shoot them. It works fine.
When you are standing or crounching it's harder to hit the target, but it's not a bug...

Tested with Hamr and 6.5mm ammo, no problems. My guess is that you might have been using the ebr or mxm. In those cases, the 7.62x45 ammo they use has a different characteristics than the 6.5x39, and so, the scopes being configured for the 6.5 round, will not produce accurate results for the 7.62. For comparison, the velocities are both 795m/s, but the airFriction coefficient for the 6.5mm is -0.00096, whereas for the 7.62 it is -0.0009324. Not sure how the ballistics algorithm works, but I'm going to guess that the 7.62 has less drag, and therefore retains more velocity at a given distance compared to the 6.5. This would result in 7.62 rounds striking high, compared to 6.5.

Keragon added a subscriber: Keragon.May 7 2016, 1:23 PM

I can confirm this.

I snipe frequently in the game (Basically all I do) and I've noticed errors up to 50m before, frequently. An example will be a target registers at 500 yards, yet the bullet lands way low and I need to use just slightly lower than 550 yards (splitting the 500 and 600 marks).

This happens on targets with the same elevation. Obviously being higher or lower than the target will have effects on the bullet.

Tested with hamr on the mxm also, and the results were remarkably similar to the regular mx, despite different ammo. Have not tested with Arco yet. Can you guys tell us specifically which weapon and scope combination you're getting this problem with? Also, are you using suppressor s, or not?

The ARCO seems to be off by a lesser degree than the RCO, but I hardly use the RCO so my comments there won't be accurate.

With both the MXM and the EBR (even now that the ammo is fixed) I have similar results for both ammunition striking far low. This is with the ARCO sight and no suppressor.

How are you ranging these targets?

I've uploaded a mission with targets at 100 through 1000 meters on the runway. Please give this a shot and see what your results are. You may need a friend to spot for you, especially for the fart argets. In my own testing on this mission, I've found that the bullet may strike low, typically by one, maybe two meters, at long distances. This may be dependent on the shooter though. I've had results varying between spot on and low strikes.

also be mindful that if you have altered the default field of view for your player, it will throw off the scopes.

Ranging the targets by using the ~ key. Lately I've began double checking the range against the map by setting a way point up over the target.

Usually my shots are only low by a few meters, but sometimes its a lot more. Its frustrating when I shoot one target at the 600 pin and then another one at the same range just more to the right and suddenly I need to be aiming more 620 yet the only thing that's changed is bearing.

I haven't changed my FOV, so I don't think the error is coming from there.

how much more to the right? 5 degrees shouldn't make much difference, but 25 will.

Why would that have an impact? The yardage and elevation doesn't change, why would aiming more left or right change the point of impact?

Normally I wouldn't say much more than 5-10 degree's left or right.

MadDogX added a subscriber: MadDogX.May 7 2016, 1:23 PM

Mass closing ancient tickets with no activity for > 12 months; assume fixed or too trivial.

If this issue is still relevant in current dev build, please re-post.