Can You Fire A Loaded Crossbow as a Reaction?

Question

If you have a light crossbow and it is loaded with a bolt, can you fire it as a reaction?

Loading: Because of the time required to load this weapon, you can fire only one piece of ammunition from it when you use an action, bonus action, or reaction to fire it, regardless of the number of attacks you can normally make.

Does this mean that you can have a crossbow loaded and then fire it as an open reaction, not needing to specify the trigger for it?

Or possibly use a bonus action to use it thus saving your reaction for later use?

Answer 1

You can not fire a crossbow as a reaction or a bonus action without taking certain actions prior.

What the loading description is trying to say is that if you are somehow able to use an ability to attack with a crossbow using a bonus or a reaction; you would still only be able to use attack once with that crossbow unless the ability said otherwise. Loading the crossbow is part of the attack and no matter which action you use when you do it you can only attack once even if you would normally be able to attack more than once, unless stated differently by that ability.

Answer 2

Yes, you can fire it as a reaction

The property states:

[Y]ou can fire only one piece of ammunition from it when you use an action, bonus action, or reaction to fire it, regardless of the number of attacks you can normally make.

It enumerates each type of action you can use to make an attack with. It does not say:

[Y]ou can fire only one piece of ammunition from it once per round, regardless of the number of attacks you can normally make.

That is, you can fire one piece of ammunition from it when you use an action. You can also only fire one piece of ammunition when you use a bonus action. And you can only fire one piece of ammunition from it when you use a reaction. This is true regardless of the number of attacks you can normally make.

What that property does not say is that you can only make one attack from that same weapon once per round.

The key here is that they limited the loading property to one attack per action.

Application: War Priest

The War Cleric's ability War Priest lets them use a bonus action to make a weapon attack when they take the Attack action on their turn. So they can fire from a crossbow with their action, and they can fire from it again using their bonus action. If someone they were in melee with tried running without disengaging first, they can make another attack using a reaction.

Answer 3

What this means is that things other than an action, bonus action, or reaction which would ordinarily allow you multiple attacks in this situation aren't affected by the weapon's loading property. Currently, the relevant action-like things that aren't in the list are: Lair actions, Legendary actions, free actions, movement, free object interactions, and not-an-action-actions. Of these, only object interaction, Legendary actions, and Lair actions can actually be contrived in such a way as to make the exception to the loading property effective.

This does not mean that you can use the listed actions to make attacks with your crossbow; it merely limits your ability to use those actions to do so if you already could.