Kiwi, I was officer in charge of all range work in my army unit many moons ago, just a couple of points....
1.If a person stands on his "Professionalism" and refuses to present their weapon for inspection, they are not a professional at all, period. No comply then no fly, period.
2. Nobody has ever been killed in a "loaded" firearm accident, they were all unloaded of course.
3. The only absolutely sure way of telling a weapon is unloaded is to stick your finger in the firing chamber while looking down the barrel. If you can see your finger wiggle, there is not a round in the chamber. If there is no magazine or ammunition anywhere in the breach and there is no round accidentally stuck to the face of the bolt, or the bolt is removed, you may consider the weapon is unloaded. The bit in bold almost ended my military career.
4. Even when its unloaded, never ever point the thing in the direction of a person or the aircraft. Treat it as if its still loaded.
5. Every time you pick up a weapon do step #3 again, even if you did it only five minutes ago.
6. Carry shotguns "broken" (unlocked). Rifles with their bolts removed and stored separately, ammo seperately again. Do not ever rely on a safety catch as your only means of security - they can fail.
7. And please please don't ever, ever, accept that a weapon does not need to be checked (step#3) because "It's broken/damaged/missing a bit" or "We haven't used it" or "it's brand new, still in its box" or "I just checked it". The first of those also almost ended my military career.
You might consider doing a firearms safety course if you are going to have to do this on a regular basis.