This bug seems to be weapon independent; I've seen it with bolts, SMGs, LMGs, and I think I was even TKed by a semi auto rifle acting up in this manner. I've also seen both the single-shot and multi-shot (fire-bolt-fire) varieties of this bug, though I don't know what causes this bug to take one form over the other.
Also, vanelle, I think you saw a different bug. I haven't encountered that one personally, but my understanding is that there is an issue when blind firing a bolt action rifle where the rifle goes fully automatic and has a random amount of ammunition.