Old School..
If the target was of unknown size, We use trip flares and claymores in a stand off mode (1K),, give them 3-4 minutes to recover and call in pre-marked artillery, wait a hour and go count coup..
If it's a small team(3-5) and small target,, sit and wait until you see the whites of their eyes,, with predesignated signal, like a trip/smoke/wp flare. Having something that calls the target attention away from you, can give you 10-20 seconds of surprise time to unload hell..
My $00.00002