Read Online Scene of the Crime by Anne Wingate - Free Book Online Page A
Authors: Anne Wingate
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fired from an unknown weapon, the firearms examiner can generally say, with a very high degree of certainty, what make, model and caliber of gun fired it. A severely damaged slug, of course, may make such identification impossible. The slug can be severely damaged in any one or more of several ways. First, it is hot as it leaves the gun barrel. As it flies through the air simultaneously piercing the air and spinning, it continues to be heated by the friction of the air molecules. A soft lead bullet, striking anything hard, will tend to splat! and distort quite a lot; a copper- or steel-jacketed bullet may distort less from the splat effect but may shatter if it hits bone or metal. On the other hand, even a soft lead bullet that passes through only soft tissue probably will have very little distortion.
A shotgun differs in this regard, in that, generally, the shot is not marked by the barrel. Therefore, it is not generally possible to say what load of shot came from what shotgun.
When the gun is discharged, the firing pin hits the back of the shell either on the center or on the rim (depending on whether the weapon is center-fire or rim-fire), marking it in a way that, like the marks of the rifling, is distinctive. Therefore it is almost always possible to say what rifle, revolver, pistol or shotgun fired what cartridge or shell.
What About Caliber and Gauge?
You've heard firearms described as .45-caliber, 12-gauge. If you're a hunter or if you've been in the military, you probably know what those terms mean. Otherwise, you don't. So here goes.
Gauge, which is used to measure only shotguns, has to do with the weight, in fractions of a pound, of what the shotgun would fire if it were firing solid ball ammunition instead of pellets. Thus, a 12-gauge shotgun would fire a solid ball of lead weighing 1/12 of a pound; a 10-gauge shotgun would fire a solid ball of lead weighing 1/10 of a pound. (I'd hesitate even to write about home-loading a shotgun shell this way. I'd be afraid somebody would try to do what I said and wind up blowing up the barrel, with probably fatal results.) Although theoretically this round ball of lead would exactly fit the barrel, I suspect the fit may be rather tight. The shotgun, remember, is not rifled. (It is possible to purchase rifled slugs for shotguns, but they are specially made.)
Shotgun shells are changing: Shotguns are customarily used for shooting wildfowl. There have been repeated incidents of ducks and geese dying by flocks from lead poisoning when lake levels dropped and the birds, instinctively seeking the small gravel they customarily have in their crops to allow them to digest their food, consumed lead shot left on the bottom of the lake. As a result, more and more shotgun shells are being made with safer steel shot instead of lead shot. Shotgun aficionados argue at great length as to whether the steel shot is better or worse than lead shot; what is certain is that it is lighter, and therefore steel shot needs to be about two shot sizes larger to have about the same shot pattern as lead shot. University of Utah student Joel Grose researched this situation in depth for a paper and reported that an ounce of number-six steel shot will have a considerably tighter shot pattern (that is, more pellets concentrated in a smaller area) than an ounce of number-six lead shot; in order to get the same shot pattern, number-four or even number-three steel shot would have to be substituted. (The number here pertains to a formula that calculates the number of pellets per ounce. For more detailed information, you might prefer to talk with the owner of a gun shop, as s/he can answer specific questions.)
Grose further pointed out that a shotgun, because of its smooth bore, cannot be at all accurate at over about fifty or fifty-five yards. These items of information might be useful in writing, particularly if your character is firing a shotgun using an old shell loaded with lead shot and then a new shell
A shotgun differs in this regard, in that, generally, the shot is not marked by the barrel. Therefore, it is not generally possible to say what load of shot came from what shotgun.
When the gun is discharged, the firing pin hits the back of the shell either on the center or on the rim (depending on whether the weapon is center-fire or rim-fire), marking it in a way that, like the marks of the rifling, is distinctive. Therefore it is almost always possible to say what rifle, revolver, pistol or shotgun fired what cartridge or shell.
What About Caliber and Gauge?
You've heard firearms described as .45-caliber, 12-gauge. If you're a hunter or if you've been in the military, you probably know what those terms mean. Otherwise, you don't. So here goes.
Gauge, which is used to measure only shotguns, has to do with the weight, in fractions of a pound, of what the shotgun would fire if it were firing solid ball ammunition instead of pellets. Thus, a 12-gauge shotgun would fire a solid ball of lead weighing 1/12 of a pound; a 10-gauge shotgun would fire a solid ball of lead weighing 1/10 of a pound. (I'd hesitate even to write about home-loading a shotgun shell this way. I'd be afraid somebody would try to do what I said and wind up blowing up the barrel, with probably fatal results.) Although theoretically this round ball of lead would exactly fit the barrel, I suspect the fit may be rather tight. The shotgun, remember, is not rifled. (It is possible to purchase rifled slugs for shotguns, but they are specially made.)
Shotgun shells are changing: Shotguns are customarily used for shooting wildfowl. There have been repeated incidents of ducks and geese dying by flocks from lead poisoning when lake levels dropped and the birds, instinctively seeking the small gravel they customarily have in their crops to allow them to digest their food, consumed lead shot left on the bottom of the lake. As a result, more and more shotgun shells are being made with safer steel shot instead of lead shot. Shotgun aficionados argue at great length as to whether the steel shot is better or worse than lead shot; what is certain is that it is lighter, and therefore steel shot needs to be about two shot sizes larger to have about the same shot pattern as lead shot. University of Utah student Joel Grose researched this situation in depth for a paper and reported that an ounce of number-six steel shot will have a considerably tighter shot pattern (that is, more pellets concentrated in a smaller area) than an ounce of number-six lead shot; in order to get the same shot pattern, number-four or even number-three steel shot would have to be substituted. (The number here pertains to a formula that calculates the number of pellets per ounce. For more detailed information, you might prefer to talk with the owner of a gun shop, as s/he can answer specific questions.)
Grose further pointed out that a shotgun, because of its smooth bore, cannot be at all accurate at over about fifty or fifty-five yards. These items of information might be useful in writing, particularly if your character is firing a shotgun using an old shell loaded with lead shot and then a new shell
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