Sure. Have 2 conductive plates separated by an insulator. Each one should be connected to the circuit in the manner of a switch. Make sure that you have redundant circuitry in case a bullet hits a vital part of the circuitry. If the plate is compromised, then it will likely cause a connection, and subsequent triggering. Alternately, you could use a thin container of mercury which when compromised, would spill out and complete the circuit.
I am not a bomb maker, just a geek that likes to think about problems and hypothetical engineering like this, and express it through his First Amendment right of free speech. Please leave me alone, as I have NO intention of making/using a bomb (baring the odd firecracker or bottle rocket). I am not a threat, and I do not need to be dragged from my house in my underwear, and interrogated for hours on end. There is nothing to see here.