Well last night I went to walmart. They had 9mm ammo. When she rang it up she only asked if I was over 21. I explained to her the law and about my carbine, she said she had never heard of 9mm rifle. We butted heads and I offered to show her the gun manufacturers website and the ATF saying it was okay to sell hangdun caliber ammo for rifles to people over 18 but not yet 21. Eventually my logic won and she stopped trying to convince me that I was trying to scam her. She then just said no, she wouldn't be able to sell it for me so I asked for a manager. The manager was confused. She said it SHOULD ask if it's for a handgun or rifle and it instead merely asked if I was 21 or not. She is going to talk to the day time manager today for me as she wouldn't just tell the computer I'm 21 because it was unethical, which I kind of understand. So today we will see how their conversation goes.