If possible, ship in the original box or another box with a ton of padding. If you don't have either on hand then a hard gun case will work fine, just be sure tape the shit out of it so no nosey CP workers decide to take a peak. I have shipped three guns in cases and never had an issue. Odd looks while waiting in line? Yep, but other than that, they don't seem to care.
Be sure to insure the item, and to pay for the signature upon delivery option as well.
My only worry about death is that my fiancÚ will sell my gear for what I SAID I paid for it.....