Also, if they are selling ammo they manufactured, they need to have a Type 06 FFL. If you have any doubts, don't hesitate to ask to see a copy of the license. If they don't have it, run, don't walk away.
Having a Class 06 F.F.L. basically tells the world that you are a TRUE Commercial reloader and not someone sitting in their basement with a Dillon 550 and two extra tool heads who goes to Gun Shows and sells his ammo in "Midway" boxes or plastic bags. To have an 06 license, you must have a Federal Tax I.D. number, pay the 11% excise tax on what you produce, also have a State resale license (In Indiana, it is a Retail Merchants Certificate) so you can collect State Sales Tax. Also, buying from an 06 licensee, odds are he has Product Liability Insurance and is responsible for any problems that may result in the use (or mis-use) of his product. Then with all of these taxes that MUST be collected & paid, there is the paperwork that goes along with them and must be sent in to the proper governmental agency.
And one must have an 06 license to purchase components in quantity and usually have to sign an agreement with the supplier that the components cannot be resold as components, only loaded into ammunition!!!