SD ammo in non SD guns shoots way higher than it should.

[Crimsonshot 0]

I was originally going to put this in the bug reports section (In fact I tried yesterday) but it wasn't accepted apparently, so I'll post it here.

While mucking around in DayZ with my L85A2 AWS, I happened upon a crash site and needed to take out some zombies quietly, so I switched to some Stanag SD rounds and targeted a zombie, putting my crosshair right on their head. I shot, and missed apparently, so I unloaded a few more rounds thinking it was user error, but nope, still no luck. So, I hopped into the armory and found the gun to be pretty accurate... until you switch to SD rounds. Here is a video outlining the problem and showing it's not just a problem with the L85 either. (Sorry for the mic quality, using an old headset).

[ImaffoI 22]

This is done by rocket to discourage the use of sd ammo in a non-sd weapon i heard. I dont know why, but thats the explanation.

[Techercizer 82]

Use the search function. This is well known and on purpose; it's due to the sights failing to compensate for the different muzzle velocity of subsonic rounds.

[Dingus (DayZ) 429]

Use the search function. This is well known and on purpose; it's due to the sights failing to compensate for the different muzzle velocity of subsonic rounds.

Why I love Arma.

[Crimsonshot 0]

Use the search function. This is well known and on purpose; it's due to the sights failing to compensate for the different muzzle velocity of subsonic rounds.

Then wouldn't it make more sense to have the bullet shoot lower than the sight?

[Techercizer 82]

Then wouldn't it make more sense to have the bullet shoot lower than the sight?

Use the search function and find out.

[Crimsonshot 0]

Use the search function and find out.

Just searched the entire forum with the broad terms "SD Ammo" and didn't come up with anything related to this, care to elaborate?

[Techercizer 82]

http://dayzmod.com/forum/index.php?app=core&module=search&do=search&andor_type=and&sid=b8541e184fc0e9d396f0d0aa78cf1b58&search_app_filters[forums][sortKey]=date&search_content=both&search_app_filters[forums][sortKey]=date&search_app_filters[forums][noPreview]=1&search_app_filters[forums][pCount]=&search_app_filters[forums][pViews]=&search_app_filters[forums][sortDir]=0&search_term=%22sd+ammo%22&search_app=forums&st=25

Second page in, a cornucopia of threads explaining things like

When you have to aim the gun below what you want to shoot, that means it's zero'd farther than the target is. When you have to aim it above what you want to shoot that means it's zero'd closer than the target is.

That being said SD ammo zeros your gun for 1000 meters, regular ammo will zero it for 300 meters.

Take your pick.

and many more like it.

Edited July 12, 2012 by Techercizer

[Valec 55]

They don't know.

That's the most absurd explanation i've ever heard, as it doesn't explain anything. Why the hell would SD ammo be zerod for 1,000 meters? Why would it be zero'd at all, for that matter, it's not a rifle. It's ammo.

Edited July 12, 2012 by Valec

[Stetzer 0]

If the sight is zero'd at a certain range, subsonic rounds should be shooting lower on the target not higher. Subsonic rounds have less velocity than normal rounds which means the bullet should start to drop a lot faster than normal rounds. Below is an image I found in an old thread. Typically, you would need to aim above the target to compensate for the extra bullet drop subsonic rounds would produce. However, Arma 2 for some ungodly reason completely changes the ballistics altogether when switching to SD rounds making them arc as soon as they leave the barrel.

I've experience this plenty of times myself, but on occasion, SD rounds in a normal weapon will shoot normally. If it's a feature, it's stupid as hell, but if it's a glitch, I guess everyone will have to deal with it.

Edited July 12, 2012 by Stetzer

[Techercizer 82]

That "ballistics change" is a combination of increased zeroing (which is why the bullet leaves the gun at a higher trajectory) and decreased bullet velocity (which is why the curve is sharper).

[lev 39]

That "ballistics change" is a combination of increased zeroing (which is why the bullet leaves the gun at a higher trajectory) and decreased bullet velocity (which is why the curve is sharper).

How the heck do you "zero" a bullet? Zeroing is a term applied to the sights/optics on a weapon. The bullet always exits parallel to the barrel bore which means the bullet can not arc upwards out of the angle the barrel is pointed at. If anything SD ammo, being subsonic ammunition has a lower bullet velocity which means it can not travel as far as standard bullet. This means if you optics are zeroed for 300m a subsonic round should hit lower than a standard round under the same firing conditions, not higher.

This, fyi, is what the ballistics of a subsonic vs standard round should look like:

Edited July 12, 2012 by Lev

[jostster@gmail.com 17]

WHY is there even SD ammo? SD (subsonic) ammo just reduces the velocity to prevent it from breaking the sound barrier. 9x19 parabellum has a velocity of 900-980 fps while the speed of sound is about 1126 fps. Because of this there is no point in SD ammo for the M9. Regular M9 mags should be able to be used in the M9 SD.

M4 should have SD rounds, however you should be able to fire non SD rounds and have the gun be a tad bit louder than firing SD rounds.

[jostster@gmail.com 17]

How the heck do you "zero" a bullet? Zeroing is a term applied to the sights/optics on a weapon. The bullet always exits parallel to the barrel bore which means the bullet can not arc upwards out of the angle the barrel is pointed at. If anything SD ammo, being subsonic ammunition has a lower bullet velocity which means it can not travel as far as standard bullet. This means if you optics are zeroed for 300m a subsonic round should hit lower than a standard round under the same firing conditions, not higher.

Agreed. I was wondering why the bullet would hit higher when it has lower velocity, it should hit lower.

[Techercizer 82]

Have you ever looked down the sights of a gun in Arma II and changed the zeroing? Where your crosshair is doesn't change a single pixel between 100m and 1000m designations; this is because in ArmA, when you zero your weapon, you're changing how high the bullet fires (equivalent to physically tilting the barrel on the gun up with range) instead of how high your crosshair is positioned.

Subsonic rounds hit high because they zero guns to 1000m. Continue to debate this amongst yourselves if you wish. I've not only shown you how to find to the answers, I've gone out and gotten them for you mysel; I've contributed everything I can to this thread.

Edited July 12, 2012 by Techercizer

[lev 39]

@spectral, just edited my post to include an image of ballistics of subsonic vs standard ammunition (they also have some sort of hyper sonic rounds but not sure what that is)

[lev 39]

Have you ever looked down the sights of a gun in Arma II and changed the zeroing? Where your crosshair is doesn't change a single pixel between 100m and 1000m of zero; this is because in ArmA, when you zero your weapon, you're changing how high the bullet fires (equivalent to physically tilting the barrel on the gun up with range) instead of how high your crosshair is positioned.

lol, do you even know what you are saying now? Zeroing occurs by changing the angle of the scope/sight. So when you aim, the tilt of the optics causes you to tilt the barrel so that the reticle/chevron/what-not is placed on the target. Zeroing has nothing to do with why a subsonic round seems to be hitting further than a standard round fired from the same rifle with the same optical settings.

[jostster@gmail.com 17]

Have you ever looked down the sights of a gun in Arma II and changed the zeroing? Where your crosshair is doesn't change a single pixel between 100m and 1000m designations; this is because in ArmA, when you zero your weapon, you're changing how high the bullet fires (equivalent to physically tilting the barrel on the gun up with range) instead of how high your crosshair is positioned.

Subsonic rounds hit high because they zero guns to 1000m. Continue to debate this amongst yourselves if you wish. I've not only shown you how to find to the answers, I've gone out and gotten them for you mysel; I've contributed everything I can to this thread.

Where are you getting this information that SD rounds auto zero your weapon to 1000m? All other weapons that allow zeroing, start out at 100m - 300m zero and allow you to adjust from there.

[Andrej Dudev 50]

I opened a similar discussion, you may find interesting informations: http://dayzmod.com/forum/index.php?/topic/16781-m4a1-ccos-aimpoint-not-accurate/