In D&D 5e, can a 5th-level fighter shoot a hand crossbow 4 times per turn using the Crossbow Expert feat?
The fighter's Extra Attack feature says (PHB, p. 72):
Beginning at 5th level, you can attack twice, instead of once, whenever you take the Attack action on your turn.
The Crossbow Expert feat says (PHB, p. 165):
You ignore the loading quality of crossbows with which you are proficient.
When you use the Attack action and attack with a one-handed weapon, you can use a bonus action to attack with a loaded hand crossbow you are holding.
Is the following statement valid?
The fighter is holding a hand crossbow. He begins his turn. He takes an Attack action; using his Extra Attack feature along with the first benefit of Crossbow Expert, he shoots twice during this action. Then he takes a bonus action. Using the last benefit of Crossbow Expert, he makes this an Attack action. He is limited to using a hand crossbow during this action. He shoots twice using his Extra Attack feature. (Assume he can do this with the same hand crossbow.)
It is ambiguous whether "you can use a bonus action to attack" means "you can use a bonus action to take exactly one shot" or "you can use your bonus action for the round as an Attack action". Or even if it does mean "you can use a bonus action to take one shot", it is ambiguous whether it means "an Attack action in which you use a one-handed weapon gives you an opportunity to shoot during your bonus action" or "a one-handed weapon attack made during an Attack action gives you an opportunity to shoot during your bonus action". (One bonus shot per Attack action, or one bonus shot per attack within the Attack action?)