A couple years ago the store I manage was purchased by another store in a different state.  We are still separate stores just with the same owner.  I was having a conversation with the manager of the other store about a negative review on Google which was over the age to purchase ammo.  Apparently they do stuff way different at the other store.  She is insisting we cannot sell .44 magnum ammo to an 18 year old unless he actually has the rifle with him.  Quote:

"The law sees it as handgun ammo. Doesn't matter what he says in the eyes of the law. Unless he had his riffle with him we wouldn't of sold to him either. I know you know this but again wouldn't of matter if he said it or not."

I don't know of any codified list of ammunition that states what is or is not handgun.  Am I wrong here?

https://www.atf.gov/firearms/qa/may-licensee-sell-interchangeable-ammunition-such-22-caliber-rimfire-ammunition-person

It’s your judgement call to make on whether the buyer intends to use it in a rifle or handgun.

That's what I thought, store policy is one thing, law is another.  I can say 100% for sure I bought a lot of .22 once upon a time where I was asked "long gun or handgun." My biggest contention with what she said was viewed as handgun ammo.  Like there's a list of all ammo out there codified in law somewhere. 🤣

Another gun store commando. So certain they are right, but 100% wrong.

I wish I would of brought my riffle so I could of bought that ammo.