[Well, he's just going to bring the entire damn gun, if no one minds, though he has his reasons for doing so; his motions in unloading it are quick - drop the magazine, remove the ammunition, slide the action and check the barrel - the sort of methodical actions that come with being incredibly practiced at what he does.]

Guns come with five rounds in them. Nothing else.

[And all five seem to have been present in this particular gun when he unloaded it, which is likely telling given that even if he's got two guns, more than five gunshots have occurred in this hotel. Furthermore, the gun seems completely clean as he's working with it - there's no indication that it's been fired at all, much less recently.

But there are five rounds on the table, all of them 9mm.]

Mikami already knows the caliber on my weapons, but you can confirm it for him, why not.