Starter pistols can be used too instead of a ‘real’ gun. At the destination they keep the bag secure for you to pickup, no getting it off the baggage carousels.

Of course some destinations won’t let you have a gun...

Ammo works too. Worked at a shop where they would have us transport a 1U server in a case that also held a single .22 round. You would fly to the location, pick up the server, and hand the bullet to the person working the desk to discard. Got the occasional dirty look, but prototypes were never lost. Empty case could be checked on the way home.

That helps protect your baggage from theft; it doesn't protect your baggage from damage.

That's what the Pelican case (with a serious padlock on it) is for.

TSA (or equivalent travel agencies) can force that locked hard case to be just large enough to cover the arm and its ammunition and not all the baggage.