Someone already answered your post, but here is the actual drawer safe used by NZ Police. I'd not go for exactly that, but instead lock the firearm in the car
in a concealment and the bolt would still come with me if detachable.
Attachment 159875
(But I'd not carry half a shotgun around. English police shot
Harry Stanley who carried a table leg in a plastic bag. His offense was being Scottish, which someone had mistakenly mistaken for him having an Irish accent and their AOS got called in. I mean, it would be OK shooting someone for
actually being Irish, no?)