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You’ve heard it on your favorite cop show, “looks like the killer used a twenty-two,” or, “he was killed with a nine millimeter.” But, if you’re curious like I was, you’re asking yourself, “what the heck is a twenty-two and what does it mean anyway?”
Well, common sense would suggest that the numbers have something to do with size and that is exactly correct. When you hear various numbers being mentioned related to bullets, the number being referred to is what’s called the bullet’s “caliber”. Caliber is a unit of measurement related to a bullet’s size. Specifically, what’s being described is the bullet’s diameter.
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To be even more specific, the caliber of a bullet is the measurement of the diameter of the slug (or projectile) part of the bullet cartridge. This is important because in some situations, the bullet casing can be wider than the slug itself. But the caliber is specifically describing the width of the slug portion. Caliber does not refer to the length or power of the bullet, but simply the diameter of the bullet.
The Bottom Line: The Width of a Bullet Determine’s Its Caliber
I know, you’re thinking, “but what’s a twenty-two compared to a nine millimeter?” Well, as with all measurements, there’s the English way and the Metric way of measuring. The metric is simple, a nine millimeter (9mm) is exactly 9mm in diameter. The English measurement is a little different. A twenty-two (or 0.22) is exactly twenty-two one hundredths (22/100′s) of an inch in diameter – or a little less than a quarter of an inch. Similarly, a 0.38 is 38/100′s of an inch, a .50 caliber is a half inch, and so on.
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I never go to Wikipedia it sux
Thanks, Gun Guy…..You laid this out in a very simple way that helped me explain this to my son…JUST what I was looking for when he asked why a .22 was so much smaller that a 9mm
Really, S.J.B…? …REALLY?!?!?
Glad to be of help, JeffreyB. That’s what I hoped to do when I started this site, so it makes me happy to know I’ve been helpful.
Gret article, Thankk YOU!!!!!
why is a .380 smaller than a .38 and why would either one be any different than a .380000
Good question, Stan. Actually the .380 and .38 special have nearly the same diameter. The big difference between the two rounds is not the slug itself but rather the bullet casing. The length of the case for the .380 is almost half that of the .38 special. So, the load is much hotter providing more velocity. Here’s a great article outlining the differences in more detail: http://gundata.org/blog/post/38-special-vs-380-acp/
Hope that helps.
According to Wikipedia, caliber is decided from the internal measurement of the barrel across the lands. The evidence for this is that a 9mm bullet is in fact not 9mm but 9.02 mm, so to my mind your article is misleading.
Well, (a) “misleading” is an inaccurate criticism. This article is about “bullet caliber” not “firearm caliber”. If I was discussing what caliber is when describing specific firearms, then I would say that it refers to the inside diameter of the bore. But I’m explaining here how to understand the difference in caliber in relation to ammunition.
(b) If you’re number one source of information is Wikipedia, prepare yourself to be mislead often. Wikipedia is a great resource, but not always 100% accurate.
GOOD replay,…