Bullshit, you can ship a stock through UPS or anyone else for that matter. It's a piece of wood, plastic, whatever. Some of the 3rd party dropoff locations do have their own policies and the one close to me won't accept firearms but will take parts including barrels, uppers and other parts. And they take your word for it. When I ran a sale on here last year, I sold off all my Mega and Aero lowers and uppers (you guys that got 'em got killer deals). All those lowers were shipped through regular UPS I believe (not a store or 3rd party) and were declared. They tracked the shipment but I don't recall them making me send them next day or anything. And they gave me no problems.
Or USPS and just mail it. They don't ask. But it's wise not to send lowers and firearms through them. Chances are you won't get caught, but if you do it's not gonna be pretty. Just not worth it. They don't like dealing with hazmat or ORM-D packages either and don't like accepting them from Fedex or UPS if you have a PO Box (so don't have your powder or primers sent to your PO Box via Fedex or UPS!). Have that sent to your home or work or some other address. Reason they don't do it anymore is that ALL USPS mail is airmail now, so they have to comply with FAA. But they'll take parts and everything else, no problem. I regularly pick up and mail out non-registered, non-restricted stuff, or did anyway, haven't done much lately. Don't know how many KAC, Dillon, Lapua, Brownells, other parts and weapon's mfg.'s, etc. boxes they've signed for me in the past, most shipped Fedex or UPS to my PO Box using PO's physical address and signing a form allowing USPS to sign for my packages, a killer service if you have a PO Box.
When I mail firearms, I take those directly to a Fedex or UPS store, not a 3rd party. Usually I'm mailing to a mfg. for warranty, so usually they send me a shipping label. If they don't, then I basically do it the same way though I think they require next day air for handguns IIRC. Fedex anyway. I generally ship directly to the mfg. or dealer and they generally send it right back to me, no dealer involved.
Sounds like some of you have 3rd party locations, "UPS Stores" or whatever, that have made their own PC policies and went overboard with it. Best thing to do is avoid 'em, call 'em out and post it at your local range, whatever. Use actual UPS or Fedex locations, or just use USPS if it's not ORM-D, Hazmat or a registered firearm part like a receiver or frame.