IMO, It is a dangerous idea to place an unfamiliar weapons system in a BOB.
A weapon system tempered by neither a knowledge of the system's limitations nor the training in it's effective use will not be an advantage in an emergency situation, and may well endanger the lives of yourself and your loved ones.
One must never think of a weapon as a "magic wand" to be waved at trouble, but rather as a last-ditch effort to neutralize an unavoidable threat.
Only experience or extended tactical training can accomplish this mindset.
(The above refers to all systems of a "weapon" and a "user", not just firearms.)
That being said, many localities do not require a permit for long arms (i.e. , a rifle or shotgun). If you are comfortable with using a long arm, a full-stock, short(18") barrel pump-action shotgun such as the mossberg 500 or the remington 870 can be valuable for defense and hunting.
Conversely, carrying an obvious weapon such as a full-size long arm will make you a target for both law enforcement and criminal elements.