Rule Four of the rules of gun safety tells us to be sure of our target and what is beyond it. The idea is to eliminate mistaken identity shootings and collateral damage downrange. It is an important rule; all of them are. But it needs to be applied intelligently.
You've heard the mantra: You are responsible for each projectile that you send downrange. Every shotgun pellet has a lawyer attached. You must not use buckshot beyond the range at which all the pellets will stay on the target. Otherwise pellets will sail past the target and cause incidents downrange.
There is a flaw in that reasoning. Most shots fired in anger miss, and this is true for all types of firearms, so there is always a downrange hazard cone in a gunfight. The frequent advice that you switch to shotgun slugs beyond very short range is questionable on that ground. A miss with a slug produces a highly significant downrange hazard, an ounce of speeding lead, and a slug has a long danger radius. It is still flying, and still deadly, at farther distances than buckshot. On occasion, a shotgun slug whizzes through its target and then continues on its merry way. If you could assure that every slug will hit (and you cannot), you have not eliminated the downrange danger. You have, though, created a different problem by using slugs. The hit probability of slugs is lousy when you compare it to buckshot. It is rather essential to hit your target, after all, and buckshot gives you your best chance.
We may as well be realistic in our thinking and say that using a shotgun always requires a conscientious downrange check, a good look, not a cursory glance. You should be aware of how much the pattern spreads and look well off to the sides of your target. If there is someone in the danger zone who is not an assailant, you are faced with a no-shoot scenario, and must deal with it as best you can.
The shotgun's danger radius can be reduced by using smaller than usual shot, but there are limits on how small the shot can be and still be reliable as a fight stopper. Using small birdshot seems to me to be a poor idea. It doesn't have a big danger radius but it lacks penetration for shooting hominids. The danger to your neighbors is reduced but the danger to you is very much increased. If, God forbid, you ever need to shoot someone, you had best use something that will stop him. Repeat after me, class: Birdshot is strictly for the birds.
I am not sure what the minimum shot size is for effective self defense. It is one of those questions that I weigh on an ongoing basis. In other words, I have not made up my mind. At the moment, the smallest stuff I have on hand for defensive use is #4 buckshot, which is not to be confused with #4 birdshot, which is clearly too small for defense. I am thinking, though, that for short range uses it might be possible to go a size or two smaller than #4 buck, with the result of increased pattern density and reduced danger radius. I will need to do some tests to satisfy my curiosity about this; I'm not sure when I'll get to it. Until then, #4 buck seems a sensible minimum.
As to the question of pellets that fly wide of the target, the danger is comparable to a fusillade of bullets that mostly miss, as commonly happens when people shoot at each other, particularly when they use pistols. People situated downrange are not safe whatever weapon you are using. When due caution is exercised to look past and to the sides of your target (and above and below) the downrange danger of the shotgun is not anything startlingly and terrifyingly different from other weapons. The lesser danger radius of shot, as compared to most bullets, gives us a bit of extra insurance. Concerns about pellets that miss, as we hear them expressed these days, are largely overblown. Buckshot was in use for centuries before we decided we needed to worry especially about it.
I regard a repeating shotgun--either pump or autoloader, it doesn't much matter--as the best personal defense firearm available. Most personal defense emergencies, and nearly all self defense shootings that are later ruled justifiable, happen at short range. The shotgun is the best short range gun, so that is the gun to have. So runs my reasoning; it seems an obvious matter to me, but if you have a counter-argument, let me know in the comments.
The most evident difficulty is that the shotgun does not hold a whole lot of ammunition and its tube magazine must be reloaded with single shells, one at a time. That at least is what is most common. There are a few box magazine shotguns around and some speedloader gadgets for tube magazine guns. But in general, what people find most practical is a tube magazine and some sort of ammo carrier--a butt cuff, a side saddle, or a belt or a bandolier--that supplies you with single cartridges. This setup offers the minimum bulk of gun and gear, thus maximum maneuverability for the shotgunner.
"If you ain't shooting, you'd better be loading." So runs the time honored advice. You must replace the shells you fire with new ones inserted into the magazine. This continuous topping up of the ammo supply assures you will not be caught with an empty gun. "Shoot and move" becomes "shoot and move, while reloading the whole time." Ideally you reload before the gun runs entirely out of ammunition, rather in the way that you avoid overdrawing a checking account--put a bit in before it all goes out. If you always operate your gun that way, you will have no need for the distracting rigmarole of reloading the gun from its chamber-empty state. You will only need to poke shells into the magazine.
There is a pitfall that you absolutely must avoid when reloading. It is possible to load a shell into the magazine backwards, and the result is a jammed gun. You must verify, by sight or touch, that the rim of the shell is to the rear when you push each shell into the magazine. It helps if your ammo carrier (bandolier or the like) orients the shells so that they always come out of the carrier and into your hand facing the same way.
That brings us to the actual method used for reloading. There are several methods, but I always use the same one, for simplicity and consistency. I like the so-called violin method. (Directions are for a right handed shooter.)
I place the flat of the buttstock atop my right shoulder, with the gun's loading port, on the bottom of the gun, facing outward to the right. My left hand retains control of the forearm and keeps the muzzle downrange. My right hand pushes shells into the port, thumb on primer. This is very positive and simple and I have a good view of the shells and the loading port. If I need suddenly to put the gun back into action, I thrust the left hand forward, pushing the muzzle to the target. If there are shells in my right hand I drop them and take up a firing grip on the gun.
If you think the matter through, you will see that your sustained rate of fire is no faster than you can reload; the time it takes you to shoot one shell and load one to replace it thus becomes your basic measure of rate. For a brief time the shotgun can produce tremendous firepower, that is, for as long as the ammo in the magazine lasts, but when you must reload the rate drops a great deal. Thus you must budget your fire intelligently, using no more ammo than the occasion requires.
Fortunately, most real-world emergencies, as contrasted to 'practical' competition scenarios, are resolved without expenditure of a great deal of ammo. Lots of cops have done just fine using the standard Remington 870 with its four-plus-one capacity. The shotgun's effectiveness and hit probability are such that you will not often need a lot of shells. Still, we practice reloading as we shoot, getting ourselves into the habit of topping off the ammo whenever we get the opportunity, because "one never knows, do one!?"
Competition shooter Dave Neth demonstrates two loading techniques, the violin method first. You can also use the violin method to reload with ammo supplied from a belt, bandolier or other ammo carrier; you do not need to use the side saddle carrier shown in the video.
The Firearm Blog has the rundown on the new Remington R-51, a sleek pocket pistol for 9mm +P. A .40 S&W version is planned. The gun borrows styling cues and locking method from the old Remington Model 51, which was an excellent pocket pistol from the 1920's era. The new gun is thoroughly updated and strong enough for modern defensive cartridges; the old-time inspiration for the new design was chambered for .32 and .380 ACP.
I consider the .38 Special snubnose an indispensable sidearm. Up-to-date small auto pistol designs like this one lead me to reconsider, or at least to say that if you do not have a .38 snub, then you ought to have one of the new breed of small automatics designed for the same niche. I formed my preference for the small revolver back in an era when the small automatics were not so highly developed as those offered today. Revolver or auto, the niche you need to fill is a gun that is small and light enough to carry with you nearly anywhere, but is powerful enough to do you some good if you need a sidearm. If you are in the market for such a thing, Remington just gave you a new choice to consider.
There is a grip safety but no thumb safety, an interesting design choice that I sort of like once I think about it. As an old revolver guy, I do not like to have to remember to flip a lever to fire a gun.
Update (12 Feb 2014): A reviewer has turned up an issue that users of this pistol need to be aware of. The slide release and its spring must be assembled as per the instructions when you put the gun back together after cleaning. Otherwise intermittent failures to shoot will result. As this is something that people can get wrong they will, according to Murphy's Law, unless they know what to look for.