CSU Armor & Cover Ballistics

WHAT IS AFFECTED

Every window in the game.
All sheet metal: gates, doors, lockers, panels, fences.
Vehicle armor plate.
All brick and masonry walls.
M69 vest, PASGT vest, M1 helmet, PASGT helmet, SSh-68 helmet.
What a stopped or defeated round does to the person wearing armor.

WINDOWS
Before: glass was rated tougher than steel, concrete and brick. A single pane took more than half the speed off a rifle round.
After: a pane barely slows a bullet, and breaks.

SHEET METAL
Before: too weak at the thicknesses gates, doors and panels actually are.
After: matched to live fire test results for real mild steel plate.

VEHICLE ARMOR
Before: rated the same as ordinary sheet metal.
After: raised with sheet metal, so plate is not softer than the gate next to it.

BRICK
Before: a thick wall stopped every round in the game, including heavy armor piercing.
After: heavy armor piercing gets through. Rifle rounds still do not, by a wide margin.

WOOD
Checked and left alone. Wood was already correct, and it is what brick was corrected against. Brick was rated tougher than wood for the same weight of material, and real test data puts it the other way round.

CONCRETE
Checked and left alone. Already stops rifle rounds, as it should.

VESTS AND HELMETS
Before: the game spread the US items far wider apart than the real items are. The M1 helmet and the M69 vest were rated twice as far apart as test data puts them. The SSh-68 was rated weaker than the thinner M1 despite carrying considerably more steel.
After: all five re-anchored on published ballistic limit data for the real items, and corrected as a set so fixing one does not break the order of the others.

BEHIND ARMOR
Before: the blunt trauma a stopped round put through a plate depended only on which plate you were wearing. A .50 and a 9mm stopped by the same vest did the same blunt damage. Distance made no difference. A round that nearly punched through did the same blunt damage as one that was nearly spent.
After: the blunt damage is based on the energy the plate actually absorbed. Caliber matters, range matters, and how close the round came to defeating the plate matters. Anchored on the certification standard real body armor is tested to. Capped so a plate that stops a round does not by itself knock you out. Armor piercing rounds are now less likely to knock a helmet off, because the same figure feeds that.

METHOD
Checked against published test data where it exists, fired at inside the game to see what actually happened, changed only where the two disagreed, then measured again to confirm.
Every figure in the included research file is marked measured, calculated or estimated.
Two are estimates and say so: the size of the glass correction and the size of the brick correction. Both directions are backed by test data, the exact amounts are not.

WHAT IT CANNOT FIX

This corrects surfaces, not rounds. It will not hide a round that is set up wrong. Vanilla ammunition is fine. Modded ammunition is only as good as whoever authored it.

For a round to behave realistically, these have to be right on the ammunition:

InitSpeed: sets what the round leaves the barrel doing. Wrong here and everything downstream is wrong.

Muzzle velocity in metres per second.

Mass: used for the blunt trauma calculation behind armor.

Projectile weight in kilograms. Grains divided by 15432. A 55 grain bullet is 0.00356.

AirDrag: sets how much speed the round has left at the range you are shooting from.

Drag times area. This is not a ballistic coefficient and does not behave like one. A ballistic coefficient goes up as a bullet flies better. AirDrag goes down.

To convert from a published G1 BC:

    AirDrag = 0.00039 * mass_in_kg / BC_G1

e.g. a 55 grain bullet at G1 0.255 is 0.00356 kg, so 0.00039 * 0.00356 / 0.255 = 0.0000054.

That lands within 13 percent against three shipped rounds. Pasting the BC into the field instead gives between twenty thousand and forty eight thousand times too much drag, so 13 percent is a good place to start. Confirm the speed at a known range afterwards rather than trusting it.

PenetrationDepth: millimetres of reference material the round defeats.

PenetrationDensity: the density of that reference material. Leave it out for steel, which is the default. Set 0.65 if your depth figure is quoted against wood.

PenetrationSpeed: the striking velocity in metres per second at which the round just achieves that depth. This is the one people get wrong. It is not the muzzle velocity. If a manufacturer states that the round defeats a particular plate out to a given range, work out what the projectile is doing at that range and use that figure.

These three together are the round's entire ability to get through anything, and they are one value tested against every surface in the game.

NOT CHANGED
No round's speed, weight, drag, damage or penetrating power.
No new mechanics, interface or dependencies.
Weapon mods work normally.