I haven't ordered any kind of ORM-d materials with natchez, but other companies I have used in the past, there was a little checkbox you had to click that basically stated you were old enough to purchase the ammunition. 18/21 and pretty much relied on the honor system.
Kind of like porn sites,you have to be an adult to access those kinds of sites, but have to click and state that you are (whether you are or not)
As for a 12 year old accessing my credit card without my knowlege, that wouldn't fly in my household and they know it.