I've shipped many many boxes of ammo all over the country without one whit of problems but I've always dealt with the hub at the airport as it's only 10 miles from my home.
NOT ONCE was I EVER challenged. I boxed up the ammo properly, slapped a blue ORM-D/Small Arms Cartridges label on it and off it went. I was never asked for any other forms of id or certificates and I always sent them to individuals at their homes.
I avoid the "UPS STORES" like the plague. They wouldn't even take a wood rifle stock for me. I made the mistake of answering their question as to what I was shipping. Consider the fact, too, that their boxes that would handle a rifle cost $40 and that's all I needed to never return to their store.
And, the idea of flagging down a UPS driver is an excellent one. Just have the label on the box attached and ready to ship and just give it to a UPS truck and away it goes. You can very easily open a UPS account on your computer and print everything you need on your PC including labels and receipts and you can set up notifications to your and your recipients email as the box travels. You pay by attaching a credit card to your account. Simple as pie. UPS is by far the easiest shipping service on the planet. I’ve shipped many dozens of firearms and hundreds of pounds of ammo in many boxes without a hitch. I thinned out my collection about six months ago and found that UPS was the way to move stuff across the fruited plain.
As for shipping ammo without a label, I would never consider it. ORM-D (Other Restricted Materials type “D”) tells UPS not to use air but only ground. While ammo is extremely safe to ship, there are strict rules about what goes on a plane and what does not. The ORM-D label keeps the box in trucks.
Rome