[denster]

I ship black powder guns by priority mail insured with delivery confirmation. I tell the clerk that is what I want, how much insurance and there is nothing liquid, fragile, perishable or hazzerdous. They put the stickers on tell me how much and give me the receipt with tracking number. I've never had them ask what was in the package when done at the post office.
If you go to Pac-Mail they will always ask, even though it is none of their business, and hit you with a nasty surecharge just to print the postage and will always give you bad info on shipping any type of gun. I only use them for UPS or Fed-Ex drop offs where I printed the shipping on line.

If you are still worried what the clerk may ask. Get priority flat rate boxes free from the post office or online and print your postage and insurance and delivery confirmation online. Slap it on the box and hand it to your mail carrier or drop it off at the post office. No questions asked.