"They sell guns but do not sell bullets."

Translation: Họ bán súng nhưng không bán đạn.

[Jessie337053]

Why is it incorrect to use classifiers on guns and bullets?

[TehVanarch]

In this case you're talking about guns and bullets in general so no classifier is used.

[ruairidhmac]

is it colloquially acceptable to say "Họ bán súng nhưng không đạn"?

[NguyenTanBuu]

No, it's really weird to me.