If you think bigger is better, you’ll love shooting 12-gauge, which is .72 caliber, and which is so ubiquitous that ammunition is both cheap and plentiful.  And if you’re going to get only one 12-gauge shotgun, get the $500 Mossberg M590 (Model #51663).  Everything on this gun is Military-spec, built to last and keep on working.  As many GI’s can testify, this is a shotgun you can take to war and back.

The beauty of a pump-action shotgun is its simplicity and reliability.  Malfunctions are hard to induce yet easy to clear (usually by just turning it on its side and racking the slide as hard as you can).  They can take a lot of neglect and keep working.  I opted for the variant with “ghost-ring” sights, which stand up from the line of the barrel, but which I have found are rugged and don’t really get in the way of anything, yet enable accurate shooting at longer distances.

This shotgun has a 20″ barrel (shortest legal barrel length is 18″) and the largest possible magazine in its frame, capable of holding eight 2.75″ shells.  It does not have a tight choke like sporting guns (which constrain the spread of the shot to keep the pattern accurate at longer ranges), but I have still taken it trap shooting and been able to reliably dust clay pigeons.  If you only keep one gun in your home for defense, this would be the one.  After all, as any defensive firearms instructor will tell you: The only reason to keep a pistol is to fight your way to a rifle or shotgun.  And given the hazards associated with overpenetration in a residential setting, a rifle is not something you would like to have to discharge in an emergency.

Theboxotruth.com features excellent penetration tests and anecdotes:  Even small caliber handguns can penetrate every wall in your house and keep going into your neighbors’, but buck shot will be stopped by a few walls.  Birdshot, for example, turns into a relatively harmless hail of BB’s after 70 yards or so even with no barriers.

If you do want to reach out and touch something at a distance, rifled slugs can be accurate out to 100 yards against man-sized targets.  With my M590 I chronographed Wolf Performance Rifled Slug ammunition — 2.75″ shells firing a 1 ounce slug (that’s 437 grains!) — at 1390 fps (with a stdev of 21 fps).  Those were relatively easy to shoot.  If you really want to hurt your shoulder or impress your friends, pick up Winchester Hollow Point Rifled Slugs.  I chronographed them at 1490 fps, but they are so painful to shoot I wouldn’t recommend them in this gun.  (Maybe in a good semi-auto where the gas system can absorb/dampen a lot of the recoil.)

One last feature of 12-gauge guns: You can pack a lot of interesting loads into the shells.  Hi-Vel has a number of examples.