One of my players wanted to use the spell swift quiver (PHB p. 279) with a magitech revolver-style weapon. As the weapon isn't more powerful than a similar ranged weapon would be with the spell (1d8+Dex base damage, 60/240 range) I'm inclined to allow it.
However, in coming to this decision, I noticed that the spell specifies that the ammunition must come from a quiver rather than any ammo container, so not a crossbow bolt case or a bag of darts or a magazine for bullets.
The equipment section specifies in its description that a quiver only holds 20 arrows. Which may restrict the spell to only arrow/weapons that fire arrows.
With the traditional image of a rapid-fire archer being a bow user it is possible that this potential RAW reading is also RAI.
That said I cannot find specification for which ammunition an ammunition-requiring weapon expends, only that you must have some ammunition to spend for the attack. RAW it seems that a sling can fire arrows (which makes no logical sense to me).
So two odd cases of RAW that might cancel each other out, rendering my question moot: swift quiver only applies to arrows/all ammunition weapons can expend arrows.
How would you read this?