The fact that there don't seem to be any official examples of +x ranged weapons also strikes me as a huge warning sign. (I'm still looking around for an example of such--if anyone knows of one, please point it out!)
"Some magic weapons specify the type of weapon they are in their descriptions, such as a longsword or longbow. If a magic weapon doesn’t specify its weapon type, you may choose the type or determine it randomly." DMG p 140, emphasis mine.
The fact that longbow is one of the examples given, and that many magic weapons do allow you to choose, says to me that even if there's no specific example, it doesn't matter. The intent is clearly to allow magic ranged weapons, as they literally just said so.![]()
According to Jeremy on twitter (sage advice link) the bonuses from magical ammo and magical bow do stack. He also explains that magic ammunition should be found/crafted one at a time (which would make hoarding lots of them quite hard).
HotDQ - magic longbow, +1. Chapter 4
Stacking ammo and bow on top of the sharpshooter feat is one of my key concerns
Only A is proven. B has not yet been.I think by this point we've proven that A) bows with +N property exists and B) bows with +N stacks with ammo with +N.