He also devised a metal-armoured double loophole that would protect the sniper observer from enemy fire. The front loophole was fixed, but the rear was housed in a metal shutter sliding in grooves. Only when the two loopholes were lined up—a one-to-twenty chance—could an enemy shoot between them. Another innovation was the use of a dummy head to find the location of an enemy sniper. The papier-mâché figures were painted to resemble soldiers to draw sniper fire. Some were equipped with rubber surgical tubing so the dummy could "smoke" a cigarette and thus appear realistic. Holes punched in the dummy by enemy sniper bullets then could be used for triangulation purposes to determine the position of the enemy sniper, who could then be attacked with artillery fire. He developed many of the modern techniques in sniping, including the use of spotting scopes and working in pairs, and using Kim's Game to train observational skills.