This idea comes from bioshock 2 the rivet gun has 3 ammunition types 1 of them being the trap rivet.

When successfully damaging a enemy the initial impact deals damage and moments later the rivet then detonates dealing damage one more additional time.

When shooting a wall or impacting any surface the projectile sticks to it, with a fair proximity range the projectile fires a round at any enemy who crosses its path dealing the same amount of damage it would if it where to impact the target and then detonate. The detonation is not explosive however. Each rivet will only impact a single target upon detonation. If introduced to the game each rivet should emit a small glowing beam signaling to both teams where they are placed and whether they are friendly or deadly.

It would be nice to see something like this for capture point or even a capture the flag game mode.