Can thrown weapons be used for the Hunter ranger's Volley feature?
Two people who DM for me say that the Hunter ranger's Volley feature, gained at 11th level, can't be used with thrown weapons, since they don't have ammunition. Can't you just count the number of throwing weapons you have as the ammunition?
Strictly RAW: Your DMs are correct. Thrown weapons do not have ammunition.
Personally, I'd consider whether multiple thrown weapons can be used in situations such as this or Horde Breaker to be strictly in the DM's prerogative. It makes a fair amount of sense that a character could be good enough with throwing knives to put multiple in the air in 6 seconds. On the other hand, it's pretty crazy to think that someone can throw multiple spears in 6 seconds, considering the windup you'd need to throw them.
Another "RAW" point against it is that drawing a weapon is a free object action. Despite it being "free" you only get one a turn. So even if you could throw multiple knives or spears, you're violating the free object action rule by drawing more than one.
In conclusion, your DMs make the rules of your game, and they've ruled that thrown weapons cannot be used in the way you're suggesting. Nothing in the rules disagrees with them. The best course of action is to talk to the DMs and explain why you want to throw multiple weapons, and listen to their reasons for disagreeing.
RAW They're right. As mentioned in the other answer, thrown weapons don't use the "ammunition" feature technically, and you are limited to one weapon draw. However the one circumstance that would be closest to being allowed, though I believe it still wouldn't quite be sufficient by RAW, is if the Ranger Hunter is holding a... "pack"? "quiver"? of darts in one hand and throws them with the other. Darts are a ranged weapon. And volley doesn't state that it must be used with a weapon with the ammunition property, merely that there must be ammunition available.
PHB 93, "Ranger; Multiattack": (emphasis mine)
Volley. You can use your action to make a ranged attack against any number of creatures within 10 feet of a point you can see within your weapon's range. You must have ammunition for each target, as normal, and you make a separate attack roll for each target.
It could be argued that with general beating specific, there may be just enough ambiguity in the reading of volley for a DM to rule that it's allowed to be used with darts.
