I use Projectile for my weapon system and UDKProjectile has two main function to handle Hit of projectiles(=bullet of my weapon):

1. simulated function ProcessTouch(Actor Other, Vector HitLocation, Vector HitNormal) // For Actors
2. simulated event HitWall(vector HitNormal, actor Wall, PrimitiveComponent WallComp) // Everything except Actors ( I guess)

the first method, the function just give me the actor which I hit and my question is How I can get that actor's physical material by first parameter ( Other ), in order to make a proper react about it ( for example a proper Sound of collide ) ...

A tricky (but hateful ) way which I knew works is, make a Trace from a little back of that actor to that actor, and use HitInfo parameter which include physical Material ! But there should be a more standard way !