I have 1K 308 projectiles in a factory bag want to sell and try to figure out what is the best way to ship. Small Flat Rate box is too small and Medium box costs more, then I saw USPS has Priority Flat Rate Padded/Bubbled Envelop, 9.5"x12.5", with no weight limit and will fit just fine. Has anyone shipped or received bullets in the Flat Rate Padded Envelop? I have not tried it before and don't know if USPS will accept it! Checked USPS website, can't see why not! I will need to put the bag of bullet in a stronger bag or sure.