All the values and ranges I'm using are all calculated relative to the BIS Short Range missile class:

Just like the SRAAMs most of BIS' values for MRAAM aren't much different than the ammo_Missile_MediumRangeAABase class values. This time we dont have to assume as much.

BIS actually has an AIM-120C and D. But we will use the AIM-120C as our datum.

Assumption #1 - the real world The AIM-120B range is 75km, AIM-120C range is 90km and the AIM-120D range is 130km.

Assumption #2 - The Armaverse AIM-120C(class ammo_Missile_AMRAAM_C) has a 12000m (12Km) max range.

Now comes the maths here is an example

   (Range of your other weapon) / (AIM-120C Real World MAX Range) = "RangeRatio"  

So:

  AIM-120B (75km) / (90km) = "0.8333" 
  AIM-120C (90km) / (90km) = "1" 
  AIM-120D (130km) / (90km) = "1.44"

Now we have the “RangeRatio” we can multiply that by BIS's 5km max range value to give us the 'Adjusted/scaled range' for our new missile.

   (BIS MaxRange) * (RangeRatio) = "NewScaledRange"
 
AIM-120B =   (12km) / (0.83) = "10 (Km)" = "10000m"
AIM-120C =   (12km) / (1.00) = "12 (Km)" = "12000m"
AIM-120D =   (12km) / (1.44) = "12 (Km)" = "17333m"

1. https://en.wikipedia.org/wiki/AIM-120_AMRAAM#Variants_and_upgrades
2. https://www.af.mil/News/Art/igphoto/2000427151/#:~:text=Range%3A%2010%20miles.

Ammo class from \A3\weapons_f_jets\config.cpp ~Line 144

class ammo_Missile_MediumRangeAABase: MissileBase
{
	model = "\A3\weapons_f\empty";
	proxyShape = "\A3\weapons_f\empty";
	hit = 200;
	indirectHit = 125;
	indirectHitRange = 13;
	warheadName = "HE";
	proximityExplosionDistance = 30;
	fuseDistance = 750;
	maneuvrability = 23;
	airFriction = 0.07;
	sideAirFriction = 0.18;
	trackOversteer = 1.1;
	trackLead = 1.06;
	initTime = 0.6;
	timeToLive = 35;
	thrustTime = 7;
	thrust = 210;
	maxSpeed = 900;
	simulationStep = 0.002;
	activeSensorAlwaysOn = 0;
	airLock = 2;
	lockType = 0;
	cmimmunity = 0.95;
	weaponLockSystem = "8 + 16";
	missileLockCone = 70;
	missileKeepLockedCone = 90;
	missileLockMaxDistance = 12000;
	missileLockMinDistance = 800;
	missileLockMaxSpeed = 777.778;
	autoSeekTarget = 1;
	flightProfiles[] = {"LoalDistance"};
	class LoalDistance
	{
		lockSeekDistanceFromParent = 2000;
	};
	class Components: Components
	{
		class SensorsManagerComponent
		{
			class Components
			{
				class ActiveRadarSensorComponent: SensorTemplateActiveRadar
				{
					class AirTarget
					{
						minRange = 12000;
						maxRange = 12000;
						objectDistanceLimitCoef = -1;
						viewDistanceLimitCoef = -1;
					};
					class GroundTarget
					{
						minRange = 8000;
						maxRange = 8000;
						objectDistanceLimitCoef = -1;
						viewDistanceLimitCoef = -1;
					};
					angleRangeHorizontal = 50;
					angleRangeVertical = 50;
					groundNoiseDistanceCoef = 0.2;
					minSpeedThreshold = 30;
					maxSpeedThreshold = 40;
					maxTrackableSpeed = 777.778;
					minTrackableATL = 10;
				};
				class DataLinkSensorComponent: ActiveRadarSensorComponent
				{
					componentType = "DataLinkSensorComponent";
				};
			};
		};
	};
	cost = 1500;
	aiAmmoUsageFlags = 256;
	missileFireAnim = "rocket_fire_hide";
	CraterEffects = "AAMissileCrater";
	explosionEffects = "AAMissileExplosion";
	effectsMissile = "FX_Missile_AA";
	muzzleEffect = "";
};
class ammo_Missile_AMRAAM_C: ammo_Missile_MediumRangeAABase
{
	model = "\A3\Weapons_F_Jets\Ammo\Missile_AA_10_fly_F";
	proxyShape = "\A3\Weapons_F_Jets\Ammo\Missile_AA_10_F";
};