Now, two other viewers say UPS told them the one-of-a-kind items they were shipping were also lost, and the shipping containers discarded -- one of those items now possibly for sale on eBay.

Rare items are shipped, then lost in the mail, only to be found for sale online. What's going on here? Here's what 7 On Your Side uncovered.

UPS requires its drivers to keep a log of items with values above $1,000, and customers can request a copy of this report. Gazeta requested a copy of the log, but has yet to receive it.

Indeed, the company’s terms and conditions show that if a customer doesn’t declare a package’s value, UPS’ maximum liability is $100 plus the cost of shipping the lost item.

In addition, UPS said only the shipper — Four Seasons Sports — could file a lost items complaint and request an investigation into the gun's whereabouts, Bailey said.

UPS requires its drivers to keep a log of items with values above $1,000, and customers can request a copy of this report. Gazeta requested a copy of the log, but has yet to receive it.

In addition, UPS said only the shipper — Four Seasons Sports — could file a lost items complaint and request an investigation into the gun's whereabouts, Bailey said.