You will get a lot of good advice here, but perhaps you should provide more details. How will you carry the weapon? Fixed-wing aircraft? Rotor? Ship? Vehicle? Tracked, or untracked?
Untracked, and as to fixed wing or rotor, I don't know. Depends on what I can get through the metal detector...
:)>
Something somewhat smaller than in ovrtaxt's post, though. I'll need to be able to keep it in my pants or my belt.