An unjammable rocket AIM-7R, using better roll control system, and a fixed aerodynamic. It is an unjammable rocket in the game, which indicates that no countermeasure is effective for this kind of rocket.
For the plane equipped with it, refer to:
https://www.simpleplanes.com/a/8ZM7xm/F-104PrimerPlus-block-2-StealthStarfighter-RM8-5-generation-land-based-version

It has a better warhead with an explosive range of 80m, and VT fuse explodes at 55m away from the target, which indicates the rocket is much more realistic.
Maximum Flight speed Mach 5.
Minimum range about 5km.

It uses 0 second to lock on the enemy and launch. No countermeasure is useful for this rocket, it would keep targeting at the enemy you selected during all the way.
Its VT fuze would be activated within 55 meters towards the enemy.
No gyroscope or piston is used for this guided rocket.
Effective range: about 15km to 40km.
It uses a complex roll control function to replace the gyro:
(clamp01(clamp01(RollAngle*rate(RollAngle))+clamp01(30-abs(rate(RollAngle)))/(1+0.03*abs(RollAngle)))*clamp(PID(0,RollAngle,0.08,0,0.001)*0.1,-1,1)/(1+(IAS)/100)