The book "point Of Impact" for which the movie is based on is much better and more believable, first off they said they had recovered the bullet that was fired at the can, how would they find it not knowing he had made a shot in the first place. Second I don't think snipers would switch shooting back and forth from left to right side as he did in this movie.
another part of the movie that made me wonder, how they knew he shot at the can and how they even found that bullet.