Crossbow of Extra Shots (+1) Only Uses One Bolt

So, I just found a Heavy Crossbow of Extra Shots [...] (+1). When I fire it, I notice that it only uses one bolt; judging by the status messages, it seems like enemies are only being hit once.

What's up with that?

When I press shift-C, the character screen assures me that I get "Shots: 2/turn."

I'm playing as a Half-Troll Warrior; I heard that bows of extra shots are the only way to get more than one shot off at a time, but I don't seem to be getting that.

I'm not sure if it's important, but my strength is 18/160 and my dexterity is 15.

I found an explanation to how it works:

In Angband, your character has an "energy" stat, which is not shown. Each game turn you gain an amount of energy which is determined by your speed (10 energy at speed +0). Whenever you reach 100 energy you get to take a turn (so one "player turn" equals 10 "game turns" at normal speed).

Almost all actions (moving, melee attacking, disarming, spiking/bashing a door, using a scroll/potion/device, putting on a piece of kit etc.) take exactly 100 energy. In some variants some actions take less time (dropping stuff, dousing your lamp), but these are minor.

The one big exception to the 100 energy rule is extra missile shots (whether granted by equipment or the ranger bonus shots). The game works out your total number of shots per turn and divides this into 100. So if you have 2 shots, each takes 50 energy. If you have 3, each takes 33 energy. Etc. It's a bit of a kludge really, but it seems to work.

Does that seem to be happening?