The eye disc has a tin hat tgt painted on it and a hole in the center. When you have it close to the eye you can watch the trainee as he releases the shot and observe flinch. Now we're going to go around for a bit about pointing weapons, but it was simple...we cleared the weapon before the class started and then we simply weren't afraid of having pointed at us. That simple. The whole exercise was in the training manual... As Peter pointed out things happen, but I did it lots and never even heard of an accident happening in Canadadoing this practice.
There was however a grenade accident in Valcartier once...live 36 in a classroom full of cadets. My woman was one of the children in the building at the time. That was a long time back...some of you remember that...