Spawn a bullet impact at a trace hit - the hit surface's impact sound and decal/particle, oriented to the surface and parented to what was hit (its nearest bone for skinned models, so decals stick to moving things). A hit object that's already gone - killed by this very shot - still gets its impact, left where it landed in the world. A pure presentation utility like Sandbox.BaseWeapon.ShootBullet(Sandbox.Scene,Ray,System.Single,System.Single,System.Single,System.Single,Sandbox.GameObject,Sandbox.GameObject,Sandbox.GameObject,Sandbox.TagSet); call it wherever you resolve a hit. Does nothing on a dedicated server or for a trace that missed.