If you could only have one gun, or you wanted one that would fit in your Bug Out Bag, but still be useful at a distance, which one would you get?
Mind you, if you only can have One Gun, it needs to be a serious caliber, at least .357 magnum if a rifle, or at least 20 gauge if a shotgun. If it's a rifle, you won't be able to get many birds with it. If it's a shotgun, you can get medium game out to maybe 100 yards, but not much beyond. Finally, it has to have some intimidation factor, so a shotgun might be best.
Sounds like no compromise is possible, right?
Wrong.
Consider:
A shotgun that converts to a rifle. No, I'm not talking about something exotic like a Drilling, or one of the Rossi barrel-swap single shots. No, you need to have at least two shots, because sometimes you miss with the first, or there are two targets to be struck.
Here's the shotgun:
That's the Stoeger Double Defense, available in 12 or 20 gauge. Note the Picatinny rails for mounting sights and/or lasers/lights. It's also an Over/Under design, which makes for a slimmer gun by about an inch than a Coach Gun. Of course, with 12-ga, you have excellent ammo commonality for all purposes from anti-materiel to armor-piercing to big game OR upland hunting. From one company, too, if you shop here.
You have only just touched one half of the possibility, however. You can load many lesser calibers with this product. That insert is 10" long, and if you select it in the 44 Magnum caliber (shown), and if you happen to have some of this ammunition, you are set to deliver a ton of muzzle energy to your target way past where that Ddupleks slug will get to. If you have a decent scope mounted to that upper rail on the Stoeger, you might notice that you still have a half-ton of energy and over 1,000 ft/sec velocity left at 250 yards with between 3 and 4 feet of drop.
If you have a more slightly-built member of the family who needs arming, get this shotgun in 20 gauge, and get the inserts in .357 Magnum. Ddupleks sells their amazing ammo in 20 gauge also, and Buffalo Bore has this amazing .357 ammo. Using the 1700 fps chart, we can see that you will have well over a half-ton of muzzle energy and almost a quarter-ton at 250 yards, with about the same drop as 44 Magnum.
Cost? List for the Double Defense is $500, the inserts are $150 each, and you will probably spend $200-$400 on an optic. I would choose a 1-4X tactical if it were me.
For about a thousand bucks, you have your One Gun, and I can hear it now, "but, but 'Dog, for that kind of money, I can have two decent guns that will do all that stuff."
What you said, lad, "two decent guns"....unlike in the movies, you can't shoot two guns at once. If you stayed with this One Gun Only concept, and carried about 5# worth of ammo, you'd be set for any encounter, two rounds at a time. If you go down, and one of your buddies winds up with your gun, your bud can operate it with 5 seconds worth of OJT.
One Gun Only, think about it.