'Phillip' was in the Sensorium, all by himself. Yes, it was against Prince Cybil's orders. However, he felt that this was the sort of thing best done without bystanders.

Namely, learning how to shoot human guns without allowing the weapons' recoil to knock him over.

He hadn't bothered to learn this when he was back on Earth. There was never any reason to. The Animorphs didn't have shredders, and Dracon beams were usually in the hands of Controllers. And using human guns was out of the question -- the last thing they wanted to do was create any connection between humans and the 'Andalite bandits'. So they relied almost strictly on their morphing capabilities and their wits.

Here however, that was less of an option. He had been able to sneak off and demorph this time, but there was no guarantee that he would be able to do so in the future. He needed to be able to defend himself in his human morph as well. So he had requested that Stacy create facsimilies of the hand-held weapons currently in use aboard the ship and set about teaching himself to use them.

Ax carefully positioned his feet and aimed at the target Stacy had set up for him and fired.