Measuring tools

Why measuring matters

In precision rifle everything revolves around repeatability. You want every cartridge to do the same thing as the last one. That starts with measuring. How long are your cases after firing? How much are you bumping your shoulder? How deep is your projectile seated? What is your concentricity? If you do not measure those things, you cannot repeat what works. And when something is off, you will not know where the problem is.

Callipers

A digital calliper is the first measuring tool you buy. It measures case lengths, overall cartridge length, projectile diameter and more. We carry callipers from Hornady and Frankford Arsenal. The Hornady is a bit heavier and sturdier, the Frankford Arsenal is a solid choice for getting started without buying the top model straight away. Both switch between millimetres and inches.

Comparators and headspace

A calliper alone is not enough for precision reloading. To check your headspace and measure your bump you need a comparator. The Ugly headspace and bullet comparator set from Derraco is a complete system for measuring both headspace and bullet seating depth off the datum of your case and the ogive of your projectile. More precise than measuring off the tip or the rim. Derraco also supplies separate Anvil Base inserts and an Up-Right comparator dial stand for those who prefer measuring with a dial indicator rather than a calliper.

OAL gauges

To determine the distance to the lands in your barrel you use an OAL gauge. The Hornady Lock-N-Load OAL Gauge is the standard for this. You use it with a modified case of the correct calibre, push a projectile against the lands and then measure the maximum cartridge length. From there you work back to your desired seating depth. Indispensable when developing a new load or breaking in a new barrel.

Concentricity

Concentricity is how straight your projectile sits in the case. Crooked seated projectiles produce more spread, especially at longer distances. A concentricity gauge lets you measure how much runout your cartridges have. We stock the Concentricity Gauge from Sinclair and the Lock-N-Load Concentricity Tool from Hornady. The Sinclair is compact and accurate. The Hornady also lets you straighten crooked seated projectiles.

Micrometers and gage pins

For those who want true precision there is the EZ Data Tube Micrometer from iGaging. More accurate than a calliper, ideal for measuring neck wall thickness and outside diameters. K&M Precision offers gage pin sets that let you measure the inside diameter of your case necks to a tenth of a thousandth of an inch. That is the level at which you can truly refine your neck tension.

Die setup

The Cheap Die's Mate from Derraco helps you set your dies precisely. You measure while adjusting your die, so you know exactly how much you are bumping and where you are. Saves a lot of trial and error.

Primer depth

Derraco also offers a Primer Gauge Set that lets you check whether your primers are seated consistently at the same depth. Five gauges in the set, so you can see if there is variation in your primer seating. Useful for validating your priming process.

Where to start

A digital calliper and a comparator set get you a long way. Add an OAL gauge when you start developing your own loads, and a concentricity gauge when you want to check your runout. The rest follows naturally as you get deeper into reloading. Get in touch if you are not sure where to begin.