Why didn't he use his gun in the prison?

Initially inside the prison interior, Tyler was getting attacked by dozens of prisoners, many armed with knives and other improvised weapons. It was like 1 vs. 50. He had an assault rifle and a pistol. Instead, he decides to hand fight. What is this writing???

Later, outside in the prison courtyard, he finally fires off a couple of rounds with his rifle. Not even an entire magazine, just a couple of rounds. Then he throws the rifle away! Pulls out his pistol, fires a couple rounds, again, not even the entire magazine, then throws it away too! Then he pulls out his knife and proceeds to hand fight with multiple assailants.

I loved this movie, but the writing in this scene is absolutely idiotic.