Many local clubs in continental Europe organize "sniper" matches. There has to be always the word "sniper" in the name of the match (sniper challenge, sniper marathon, you name it). In many cases they specify in the rules that you cannot use any rear bag while shooting prone. I never served in the military, so please kindly help me out here. Is it the case that snipers are trained to shoot without any rear support, just a bear hand under the butt stock?