I scored a complete M14 bolt and trigger group on another forum. I confirmed the terms of sale, bought my USPS money order, and placed it in a USPS Priority flat-rate mailer. I used a pre-printed shipping label from my office correctly addressed to the seller. 24 hours later the same mailer was delivered to my office. Assuming it was returned for some mysterious reason, I confirmed the address and went back to the post office. The clerk advised that it must have been entered into the system incorrectly, so she “fixed” it by writing “TO:” next to the seller’s address. 48 hours later the same package arrives at my office. Mind blown. I sent it out regular mail the 3rd time. Nice job USPS.