Well, Its a shady move, very grey, but it IS LEGAL.... Very few fields or tourneys or anyone mentions it as illegal... If you use it and it works, great (although, I hate it)....
But if you try to use it, and you get lit from head to toe... GREAT.....
Bottom line is that if a player doesnt have a plug, or his hand in the air (which means your dead even if you arnt). Shoot em. If they are dead, and you hit them, politely tell them that they need to plug the gun or raise thier hand or loudy say "HIT"
If they raise thier hand, then shoot you... they cheated, bottom line.
I have to deal with this in a tourney this weekend, sux to be on the recieving end. It usually doesnt work, but when it does....