January 14th, 2012

Videos Show Functions of Hornady Concentricity Gauge

UltimateReloader.com created an informative video that shows how to use the new Hornady Lock-N-Load Concentricity Gauge and Ammo Straightener. This tool can measure run-out on both the bullet and on the case-necks. Run-out is deviation from the cartridge centerline axis. Too much run-out, i.e. poor concentricity, can reduce accuracy, although when you seat bullets into the lands, a certain amount of bullet self-straightening can take place.

Hornady Concentricity Gauge

Hornady Tool Supports Cartridge on Both Ends
The new Hornady Concentricity Tool supports the case at two ends. As a result, the Hornady Tool will tend to yield lower run-out figures than a tool such as the Sinclair concentricity checker which supports the cartridge on the case body alone, giving the bullet unrestricted movement as the case body is rotated. As UltimateReloader explains: “Each measurement tool measures run-out differently, so you’ll need to factor that into your goals for your own match ammunition.”

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Bullet ‘Straightening’ with Hornady Concentricity Tool
The Hornady Tool can be used to push seated bullets to one side or the other, reducing measured run-out. The Hornady tool has a threaded pusher that side-loads the bullet. As you screw the pusher inwards in you can see the run-out on the dial indicator decrease. That straightening process is shown in the Hornady-produced video below, at the 25-second mark. In Sinclair Intl’s Reloading Press blog, Pete Petros reports: “It can take a little bit of trial and error to get this just right, but it does work.”

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Is Bullet Straightening Really That Effective?
This bullet straightening procedure, whether done with the Hornady tool or other device, is a somewhat controversial technique. Some folks say that straightening bullets simply transfers run-out back down to the case neck. Petros notes: “One concern that comes up is what are you doing to the neck of the case in terms of neck tension.”

On the other hand, many shooters claim their ammo shoots better after they straightened rounds which initially showed excessive run-out. One Hornady Concentricity Tool user writes: “The straightening feature on the Hornady tool makes bullet/case concentricity easy to correct and after using this tool, I wouldn’t be without one. Variations on [my] cast bullets have gone .020″ and when straightened, I can get down to below .001″. It takes a bit of practice, but it’s possible to make every round straight. At the 100-yard range yesterday using my straightened rounds … five-shot groups averaged .500. Before I would always have flyers and now I can see why this time I didn’t have any flyers. Straight rounds produce more consistent groups!”. Read more.

Bullet straightening with the Hornady Tool or other devices can certainly make a difference in run-out that shows up on the dial. Whether that improvement in perceived concentricity actually produces better accuracy remains an open question. Using high-quality dies with good bullets, seated in good, straight brass, you should be able to load ammo with very low run-out from the get-go. It may be better to try to achieve low run-out during your normal loading process rather than rely on the “band-aid” of bullet straightening as a last resort. On the other hand, if you are starting with factory-loaded ammo, re-aligning bullets in the case-necks may be a useful exercise. We invite our readers to comment on their experiences with bullet straightening. Has the straightening process worked for you?