This requirement is designed to be hard, and as such is a major red flag to me.
What else is this company going to be difficult with?
Can i only get customer support or cancel my account in person, between 9-4 on the 2nd Friday of the month?
I would consider alternatives, if possible.
.308 is 7.62, civilian measurement vs military (there’s actually implications related to pressures, sidewall thicknesses, machining tolerances, but yeah same same)