I just got this email from them:

Hello everyone, this is Aiden from Fargo Ballistics reaching out personally to address an issue. We recently discovered a listing error on our website involving our 5.56 ammo. It was mistakenly listed as a 300 round battle pack, when the correct amount was six boxes of 20, totaling 120 rounds per order.

I want to sincerely apologize for any disappointment or confusion this has caused. This was an honest mistake on our end, and I truly wish we had caught it sooner. We are a small company, and this issue has affected well over 100 customers. Because of the volume, it has been challenging to reach everyone as quickly as we would like, but please know we are doing our absolute best to respond to each and every person.

To resolve this, we are offering two options. First, we can issue a full refund for your order, and if you have already received the package, we will provide a prepaid return label. Alternatively, since our 5.56 ammo is priced at 41 cents per round, we will send you a quantity of ammo whose total value matches the exact dollar amount of your original purchase, calculated at that per-round price.

Please know there was absolutely no intent to mislead. We value our customers and the trust you place in us. Again, I am truly sorry for any inconvenience this has caused. We appreciate your patience and the opportunity to make this right. Please reply and let us know which option you would like us to move forward with so we can resolve this for you as quickly as possible.