This movie is called Looper. The eponymous character is one of many so-called "loopers," time-traveling assassins. So if this wall file is for all the loopers, the apostrophe should go at the end of the word. As it is, the sign applies to only one looper, which is a less-credible interpretation, given that the sign refers to multiple "guns." This could be a gramatically-correct sign, but only in the third- or fourth-most-obvious reading. The safer bet is that someone just threw a random apostrophe in there.
Nine thumbs down.