Forget the lock, just remove the bolt.
I'm a fan of attaching a normal lock through the receiver bridge; put the bolt in the console or glovebox if you are in transit.
Put the guns in the the gunsafe and the bolts and gunsafe keys in the Combination safe.
Then if I lose the key for the lock it's not a drill situation but rather a Dremel / Die grinder to free the gun up again.
Forget the lock, just remove the bolt.




























