Reloading: Cartridge and Bullet Concentricity Tests for Hunting |

If you hunt and shoot beyond 200 yards, bullet and brass concentricity (wabble) can matter. Experienced long range shooters call it “runout.” I have shot at 600 yards at targets on occasion but rarely checked for concentricity/runout till prepping for this falls moose hunt.

Accordingly, I just purchased a Sinclair Concentricity gage to check for runout and to see groups improve. The idea is to eliminate fliers! But that required me to do more brass case prep too. That must have helped as well. Some swear by it, some don’t.

First tests were for the case neck on those I had already full length resized a week earlier.

After checking 30 cases, half were at .003″ or greater runout (wobble), half were less. Some long range hand loaders suggest that 0.003″ is the max runout.

What to do?

I ran these .003 cases back through my full length sizing die a few times, rotating 90 degrees and retested. Runout (wobble) improved to .0015″ or less.

Next is to load some bullets and retest for bullet runout.

All bullet retests for runout were 0.003″ or less. Nice!

Doing this test suggests that the bullet is better aligned to enter the rifling nearer to parallel. So lets see some targets…

Below this Nosler 168g ABLR group shrunk from 2 inches to 1 1/8 inch group at 150 yards is an example of what the Sinclair Concentricity Gage did for me. Sub-MOA groups below!

The next picture below is of the same 168g ABLR bullet at 150 yd distance but the OAL was longer (0.020 off the lands).

The 1/4 inch difference in grouping photos was probably me. But you can see these are both sub-moa groups.

Lesson learned! To establish a best in class reloading process with or without the gage.

Good Shooting!