Focus on Safety
A Matter of Calibre
When calibre is mentioned in regard to firearms, we usually think it’s to do with the size of the projectile. Broadly speaking, this is true. However, there are some different systems for describing cartridges. We will look at some common examples below.
9mm Luger
This cartridge made its debut in 1902, and was first used in the famous automatic pistol designed by Georg Luger. The 9mm Luger cartridge was first used as a military round and was referred to as the 9mm Parabellum (from the Latin “for war). It is also a NATO standard cartridge for pistols and sub-machine guns; hence some publications refer to it as the 9mm NATO.
The European designation is 9 x 19mm, meaning a 9mm bullet seated in a rimless cartridge case 19mm long. (If the cartridge was rimmed, it would be referred to as a 9 x 19R). For this reason, many European firearms simply carry the 9 x 19 designation. The photograph above shows two 9mm Luger cartridges alongside a .22LR cartridge for comparison.
What does +P and +P+ Mean?
Any cartridge with +P or +P+ designation means that it is loaded to a higher pressure than standard, and may not be suitable for your firearm. If you have any doubts as to whether your firearm is compatible with +P ammunition, seek expert advice.
Military Grade 9mm Ammunition
Any cartridge with +P or +P+ designation means that it is loaded to a higher pressure than standard, and may not be suitable for your firearm. If you have any doubts as to whether your firearm is compatible with +P ammunition, seek expert advice.
38 Special
Released by Smith&Wesson in 1899, the .38 Special isn’t really a .38 at all. The bullet diameter is actually .357ʺ. Originally known as the .38 Smith&Wesson Special, it is a rimmed cartridge originally intended for use in revolvers, but now can also be found in automatic pistols as well as rifles.
In 1935, Smith&Wesson released the .357 Magnum, as many law enforcement agencies felt that the .38Special lacked stopping power. The .357 Magnum uses the same diameter bullet as the .38 Special; however, the case has been lengthened slightly. This is to stop inadvertent chambering of a .357 Magnum round in a .38 Special revolver. However, a .357 Magnum revolver will quite happily chamber and fire a .38 Special. The photograph below shows a .38 Special (L) alongside a .357 Magnum.
Shotgun Cartridges
Shotgun relate to the diameter of a lead ball. Therefore, a 12 gauge shotgun shell is the diameter of a lead ball weighing 12 to the pound. A 20 gauge shell is the diameter of a lead ball weighing 20 to the pound, etc. The exception is the .410 gauge. The .410 shotgun is .410ʺ in diameter.
Shot size is given a number. The bigger the number, the smaller the size. In the photo above, the 12gauge shell is loaded with No. 7½ shot. The 20 gauge shell beside it is loaded with No. 4 shot. Larger size shot are given letter or number designations. (E.g. SG, which is an English designation, is the equivalent to American 00)
Other descriptors for shotgun cartridges are length of the case (e.g. 2¾ʺ or 3ʺ), and sometimes the weight of shot carried (Usually in grams, sometimes in ounces). Older ammunition sometimes carried a “dram equivalent”. A dram was an Imperial measurement, with a standard 12 gauge 2¾ʺ load being charged with 3 drams of black powder. When smokeless powder came into vogue, many manufacturers used the dram equivalent so shooters knew how powerful the load was.
Safety considerations for Shotgunners
As can be seen from the previous photograph, there is not a lot of difference between 12 and 20 gauge shotgun shells. Accidents have occurred over the years when a 20 gauge shell has been stuck in a 12 gauge gun barrel, then having a 12 gauge shell loaded into a seemingly empty gun,
3ʺ shells should only be used in guns marked accordingly. A 2¾ʺ shell can be used in a 3ʺ chambered gun, but not the other way around.
Proof Marks
Older shotguns may only be proofed for use with black powder. If in doubt, seek expert advice before using modern smokeless cartridges in an old gun.
Steel Shot
Many jurisdictions have mandated the use of steel shot for hunting. As steel is much harder than lead, it should only be used in guns proofed for steel shot.
Reading the Fine Print
Whether in the owner’s manual or on the ammunition packaging, in shooting, as in life in general, it always pays to read the fine print.
Until next time, have a happy and safe shoot!
References: Cartridges of the World 13th Edition
Winchester Ammunition Catalogue