Wednesday, January 5, 2011


Shotguns have an aura about them that makes them unique among weapons.  Maybe it’s the size of the shell, or maybe it’s the amount of damage they seem to do, whatever it is, it’s very often over-rated.

Shotguns come in sizes that range from .410 bore to 10 gauge.

A 410 bore is actually a hole 0.41 inches in diameter, the same as a .41 magnum or 10mm pistol, and slightly smaller than a .44 magnum.  It’s the only size that doesn’t follow the standard convention explained below.

All other shotgun gauges are based on the number of lead balls of that diameter that it would take to equal one pound.  This means that smaller numbers have bigger holes.  Modern shotguns come in the following sizes.
28 Gauge
20 Gauge
16 Gauge
12 Gauge and
10 Gauge

In the past, sizes of 6, 4 and 2 gauge shotguns were used, but these were more like cannons.  Of the above list, only 20 and 12 are in regular use.  The 10 gauge is starting become common, but it’s a big round that few people will choose to shoot if a 12 is available.

A normal round consists of a case, primer, powder and bullet.  A shotgun shell is the same, in principle.  The case can be called a Shell, or Hull.  It still has a primer in the back, but only the very back is made of brass.  Most of the shell is plastic, and some are layered paper, like cardboard.

The powder charge sits in the bottom of the shell.  Above that is something called a Wad or Shot Cup.  The shot cup is usually a plastic thing that has a disc on the bottom, a few columns of plastic on top of that and a tall cup with four petals, like a flower.  Inside this tall cup is the shot.

Shot size is determined by number.  #12 shot is the smallest.  #9 is bigger than #12, and #8 is bigger than #9.  #7 is about the smallest used for hunting, but #8 or #9 can be used for sports like trap and skeet.

The number of pellets in the cup is determined by weight.  Usually about 1 oz, or 1 1/8 ounces are used in a 12 ga.  Since the weight of the shot stays about the same, but the pellets get bigger, the number of pellets in each round decreases as shot size goes up.

By the time we reach #0 buckshot, they are slightly larger than a .30 caliber bullet. #000 buck is larger than a 9mm bullet.  That means you only have 6 to 10 pellets per shell.  The thing to remember though is that those 6 pellets are going the same speed as a 9mm bullet and are nearly as heavy.  From the target’s point of view, it’s getting hit with six 9mm bullets at once.

That brings us to the spread of the shot.  Obviously, if there are only 6 pellets there is a good chance that a small object will be missed by most of them.  That’s an advantage to using smaller shot.  The number of pellets per square inch actually goes up very quickly.  Think of it this way.  If you were to hang a 12 inch pizza at the right range so that 100% of the pellets hit inside the pizza, six pellets of #000 shot will mean that there are at least 2 of the 8 slices with no shot in them at all.  On the other hand, with the 410 pellets of #8 shot, every slice will have about 50 pellets in it.

That’s where the great trade off comes in.  Those 6 pellets of #000 are going to blast through the target and keep moving.  Those smaller pellets won’t.  They will hit the surface, maybe get an inch or two in, and stop.  It’s possible to survive a direct hit from bird shot because they don’t have the mass to hold onto their momentum.

That might be a tricky thing to understand, so here’s a more common real-world analogy.  In soccer, or football if you live outside the United States, it’s a valid tactic to jump up and hit the ball with your head.  The ball is hard, but it doesn’t weigh much.  A bowling ball is about the same size, but weighs up to 16 pounds, (7.25 kg).  If you jump up and hit that with your head, it will have a much different outcome.  The reason is the momentum.

Momentum is a physics term that basically means that something wants to keep doing what it’s doing.  A ball moving through the air will keep moving until the air slows it down, gravity pulls it down, or it hits something that stops is.  Bullets and shotgun pellets are the same way.  They will keep going until something stops them.  More momentum means that they will be harder to slow down or stop.

For momentum, mass is more important than speed.  Heavier things are harder to get moving, but they are also harder to stop.  Our buckshot is heavy and moving at 1400 feet per second.  Out birdshot is light and moving at 1400 feet per second.  When both hit, the birdshot will stop almost instantly, while the buckshot will keep going.  Getting shot in the chest with a full load of birdshot will suck in immense ways best described with lots of profanity, but there is a good chance that none of the pellets will penetrate more than an inch or so into the body.  Buckshot on the other hand will go right on through.

That brings us to the “choke” of the shotgun.  The Choke is a term used to describe the shape of the end of the barrel.  An Open Choke means that the barrel is the same diameter inside all the way from the chamber to the muzzle.  A Full Choke means the end of the barrel is slightly smaller than the rest of it. 

Why would this matter?  For the same reason flashlights have an adjustable beam.  A full choke will keep the pellets together longer, giving the shotgun more range.  Similarly, a longer barrel will keep the shot from spreading as quickly.  This is one of the reasons that “sawed off shotguns” are viewed as being more destructive than other types.  At a range of about 20 yards, a long barrel with a full choke might give a pattern of under 8 inches.  That is, nearly every pellet inside an 8 inch circle.  That same round from a sawed-off shotgun might make a 20 inch pattern, which would make hitting more than one person per shot a definite possibility.  This ability to hit more than one person per shot, combines with the extra concealability of them made a sawed-off a brutally effective close combat weapon in bar fights.  Their effectiveness drops off rapidly as the range increases.

Another thing that gives a shotgun an advantage over other guns is the ease with which it can be loaded with other things.  With a rifle or pistol, you have to be very careful with the type of bullet that goes into the casing.  The diameter must be just right.  It can’t be too light or too heavy.  If the bullet is pure lead, it can’t go faster than 1500 feet per second.  There are all sorts of rules.  Shotguns don’t really care about that stuff.  If it fits in the shell and doesn’t weigh too much, it can be fired.

Got a vampire problem?  Load a shotgun shell with toothpick fragments.  One of them is bound to hit the heart but you need to get close.  For werewolves you can break the tines off of silver forks and use the same trick.  Want to frame a guy?  Get hold of a bullet from his gun and load it in a shell surrounded by packing material or rice.  Need to put down a big critter from a long way off?  Cast a .75 caliber lead ball; they just fit and are still really accurate out to 150 to 200 yards.

Anything that fits inside the shell can be fired.  There are some myths and legends out there that firing part of a roll of dimes can be super lethal, but when tested on Mythbusters, it was shown that dimes slow down way too fast to be practical.  The point is, you can fire freaking dimes from a shotgun.  Rock salt is a classic load to keep trespassers away.  It just breaks the skin and stings like the dickens, but probably won’t be fatal.

Military loads include small signal flares.  Fish and Game officers have access to firecracker loads that work like a grenade launcher.  There are even loads that fire a jet of flame out of the shotgun like a flamethrower.

Shotgun actions can be just about any type, from single shot break actions, to pump or lever, to semi-automatic.  Just about any configuration used in a rifle can be used for a shotgun.

A final note on ammunition.  Back in the late 80’s or early 90’s, it was found that waterfowl in hunting areas were eating a lot of lead shot when they’d feed.  Because that’s actually poisonous, laws went into effect in many places to restrict the use of lead shot pellets.  Copper, steel, or plated pellets were made available, but these have other drawbacks.  Steel is much less dense than lead, so for a given diameter, the penetration is less.  Steel is also much harder than lead, so the shot does not deform when going through sold objects.  The same car door panel that might stop lead buckshot will probably not stop steel shot. 

If you have a victim turn up in a duck blind in 2010, and he’s got #7 lead shot in him, your killer almost certainly didn’t buy it recently.  If that’s something that will matter, research it.

No comments:

Post a Comment