How to use calipers? – 3 common uses

A set of calipers in the reloading room is a staple of the craft. Everyone from a novice to a master hand-loader is always within a stone’s throw of a pair.

The book The Art of War says, “Your defense is only as good as your weakest point.” When it comes to today’s subject, I like to say, “A set of calipers is only as good as the accessories you combine with them.”

I will go out on a limb today and tell you what company’s add-ons I use. Before I get to 500 emails, the answer is no: I’m not getting anything for putting this company on the corner in a pretty dress.

Short Action Customs attachments and a good set of calipers are hard to beat.

Here is how to use calipers. – 3 common uses

Number one
Correctly measure your bullet distance to the rifling.

With your calipers and a SAC bullet comparator, you can start on the right foot by measuring the point where the bullet ACTUALLY makes contact with the rifling. (Most do not.)

You can adjust the bullet seating depth, improve your accuracy, and ensure safety to ensure your bullet isn’t jammed into the rifling/lands. (This isn’t good.) If that occurs, your chamber pressure skyrockets. I would avoid that situation unless you enjoy picking little pieces of metal out of your face.

Number two
Set up your headspace/shoulder bump.

You can measure your fired cases to assist in setting up your full-length die properly.

Chambers specification prints are not always what they are supposed to be, which is primarily a problem with factory rifles. Hell, most of those manufacturers refuse to give you the specs even when you ask politely.

Suppose you have a perfectly fire-formed case for your firearm.

You can now make good use of your calipers to get those critical numbers on your own. Yes, you can slug your barrel, but my girlfriend says I’m not supposed to play with molten lead.

When setting up your full-length sizing die, you need to know what those numbers are if you don’t know where to begin. How do you know where to go?

Number three
Setting your neck tension

Many questions I get ask what bushing to use when setting up neck tension?

A loaded round, a fire-formed case, and a set of calipers will answer that question.

To measure the neck diameter of a loaded round, take that number and subtract whatever neck tension you want. You now know the correct size bushing.

What is the difference between a $60 and $200 pair of calipers?

An expensive set operates very smoothly when opening and closing, and it feels like skating on ice. This is nice, especially if you have damaged hands, as I do.

The cheaper ones tend to operate like a truck on a road that seriously needs repair work.

The more admirable set typically has better resolution. Also, the acceptable amount of error is smaller.

Yes, if you read the small print, you will see that ALL calipers have this.

I hope you have enjoyed this article on three common ways to use calipers. At some point, I will probably write an article on other uses of this tool, but that will be for another day.

Remember, shoot better than me. —Mac R.

Disclaimer: Reloading/handloading, like many things in life, can be hazardous to your health. You take full responsibility when performing these procedures. 5 Gun Nation is unliable for your decisions. Don’t be an idiot, and if you are, it is not our problem.

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