Firearms Terminology: Guns for Beginners

By Dan Zimmerman

Reader Anner writes:

True Believers get all wrapped up in proper firearms terminology. Avoid that next lecture from the old coot behind the counter by studying this partial guide to proper firearms terminology:

Caliber – The diameter of the firearm’s bore, expressed as a fraction of an inch. “.30 caliber” is 3/10 of an inch wide. Depending on manufacturer’s specifications, this may denote the diameter of the bullet, cartridge mouth, barrel lands, or barrel grooves. Europeans generally measure barrel lands, while American manufacturers use barrel grooves (which is usually the actual bullet diameter). When ammo manufacturers create a new cartridge, they need it to sell. They will often choose a name that does not accurately describe its actual size. For example, .223 Remington is actually a .224” bullet; .300Blackout is actually a .308” bullet. Reference a reloading manual or the manufacturer’s website for accurate specifications . . .

XXmm – A metric version of denoting bullet diameter. 9mm is the diameter of the bullet, barrel, or related object. Again, Europeans differ in what they actually measure.

Caliber vs. XXmm vs. What ammo do I buy? – When in doubt, look at what’s imprinted on the barrel and purchase ammunition identical in nomenclature. …Read the Rest

Source:: Truth About Guns