quite apart from any regulatory Hoops you may be required to negotiate... perhaps a couple of thoughts to prevent any Whoops ;-)
Keep the business-end of the weapon pointed aft... could be daft, but there's less likely to be meat bags or critical bits in the direct line of fire of accidental discharge in that direction
Store the ammunition and the weapon SEPERATELY. Widely, IMO, preferably under PinC supervision
If you can, separate the bolt and/or firing mechanism and store them widely apart, again IMO, preferably under direct PinC supervision
In years past, FTDK and I have crossed swords over this very topic... I don't want to reopen old wounds or restart a discussion well past it's use-by date. I'll state clearly, here and now my ignorance of weapons is massive. My respect for their potential is proportional. My respect for my passengers and the safety of my airframe must be equally, proportional.
My knowledge of or respect for those seeking carriage of weapons must equally be proportional. I don't know You, I don't Know your background, experience or training -or your attitude or motives for that matter, so my personal response as PinC must also be proportional: if you can't prove the ABSOLUTE safety of the weapon you wish transported, it don't travel.