So when I was watching the dub of episode 18 of Geass r2, I noticed something. When Shinkirou was fighting with the Lancelot it just simply fired it's laser normal, and against the Tristan it even showed there was no crystal in there when it opened, but when it is fighting Lucanio's mech, it did have the crystal.
Can the crystal store itself somewhere cuz the way it seemed to go from fighting lancelot to fighting tristan to fighting mordred i don think it could have had a chance to land in the middle of the battle and get a replacement crystal.