Shooting Units: Understanding caliber

Confused? You will be.

Complete-Rifle-Ammunition-Guide-Comparisom-1024x431

In short, caliber is the measurement of the internal bore of a barrel. And that is about where the simple description ends. You see, because most modern barrels have rifling, there is actually two places you can take this measurement from. The lands, which are the high points in the rifling, or the groove, which are the low points. Generally, the US is going to measure from the groove, while the rest of the world will measure from the lands.

Generally, where a caliber bore measurement is given in inches, the inches can simply be replaced with ‘cal’. For example – .308 cal is a bullet generally .308 inches in diameter.

However, imperial isn’t standard in a lot of the world, so metric can also be used. For example, the .308’s close relative, the 7.62×51mm NATO is a 7.82mm projectile in a 51mm lengthed case for a barrel with a land to land bore of 7.62mm. However, because just using one or the other would be too simple – you also have manufacturers putting out hybrids – i.e. the 7mm-08. This is a .308 (imperial) cartridge, necked down to fit a 7mm (metric) bullet.

Then we have wildcat and homebrew cartridges that really just get named however the maker wants.

Rifle Setup Service

$ 750 /day
Spend a day learning how to properly setup your rifle, including stock adjustments, scope mounting, eye relief and more.

Despite what they may say, many stores do the absolute minimum when it comes to setting up your new firearm. Learn how to get the most out of your investment.
  • Properly Zero'd
  • Setup for you
  • Basic ballistics
  • Ready to go

Popular articles

Whoa whoa whoa… where did Precision Shooter go?

While it would be easy to say that rebrand was a result of the tragic events in recent history, it was actually...

Changes in the Semi-Automatic Classification System

I have been quiet since Friday, and for good reason, but let's try and clear up some of the confusion about today's firearms law announcement.

The Swarovski dS – Scope, rangefinder, ballistic solver.

It's the pinnacle (price wise at least) of 'smart' optics. But does the price of the Swarovski dS really equate to value? Like many things premium, it's a yes, no, yes, kinda answer.

Matching twist rate and bullet weight in rifles.

The are many benefits to understanding and matching the twist rate of your barrel with the projectile weight you are using. Primarily, accuracy.

The Stage 1 is for sale. Again.

So, I finally blew it up. The engine in the Stage 1 now has a fairly large hole in it.

Stop the Bleed. Prac Med’s IFAS Kit first look

So, should you, are someone near you have a major issue with losing a LOT of blood, do you have the resources on you to stop it?
Kerry Adams
Kerry Adamshttps://thebloke.co.nz
A constant learner with an inquisitive mind, Kerry created Precision Shooter as a way to share what he was learning from the community of experts he found himself surrounded by.Somewhere along the line, he picked up one or two things himself. But don't call him an expert.
I know. We all hate popups.
But, the fact remains that eMails are the best way for us to keep you up to date with what is going on at The Bloke.Join over 17650 others who are part of The Bloke community - every week you will get a short update from me. Be the first to know about new resources, upcoming events, courses and more.
We respect your privacy. No SPAM. Ever. Hit escape to make this go away. Apologises if you see this more than once. That's what cookies are for... ;)