Thoughts or Experience With This Concentricity Gauge
- Thread starter Stud Duck
- Start date
That one looks more complicated than it needs to be. I use this one from Sinclair ... and it's awesome. Plus, that much "stuff" at the low of a price is a little suspect.
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SINCLAIR INTERNATIONAL Concentricity Gauge With Dial Indicator SKU: 749007305 | Brownells
Check out the SINCLAIR INTERNATIONAL Concentricity Gauge With Dial Indicator SKU: 749007305 available Online at Brownells Today and many more Concentricity Gauges products are available in our Reloading Department.
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I would think a machinist would tell you that rolling the case around and assuming the body is a perfect zero reference and a perfect circle accurate to 0.001" and it's rotating on a true centerline of the circle is ridiculous. If I had to guess I would think the run out on the body is around 0.001". Maybe that's good enough. The real rabbit hole is if you don't like the run out what do you do about it. Do you buy a new press and dies and hope it improves the run out. Guys on this website can tell you how they improve run out. I cannot. I shoot 2 accurate varmint rifles. I am not trying to win matches. The replies will be interesting and informative.
Food for thought.
Different strokes for different folks. You might meet Alice in the rabbit hole so be careful.
Shooting at the varmint precision level, I can tell you that "run out" has no influence of performance in the field. If you use high quality dies and rotate the case when seating as suggested by Sierra, you can minimize run out to an acceptable level performance wise.
Ruger15151
F-Class Shooter (6BRA and WIN 284)
I shoot long range F- class and went down that rabbit hole years ago. We shoot at a small 5" dot at 1k yards. Let me save you some time. It doesn't matter on target.
There are several things that can cause runout that you can't control regardless how much money you want to spend.
The most obvious.... unless you turn your brass, just the difference in neck thickness on either side of the neck will cause run-out which you will never remove. I use premium Lapua brass and its still varies .0005-.001 in thickness from side to side.
Furthermore, the throat in your chamber is only about .0005 larger than bullet diameter. That removes most of the concentricity issues when you chamber your round.
The best use of a concentricity gauge is to check a new press or die just to make sure there isn't an abnormal amount of runout issues with it. Then, for most of us, the gauge just gets put back on the shelf to collect dust.
I would advise spending you time and money on good barrels, brass, and bullets instead.
I bought a Hornady gauge and went down that hole. Lots of time and it did not tighten up any groups. However, it is interesting thought. There’s no way that bullet is gonna hit your lands and groove perfectly straight, but it has a good theory behind it.
Thank you, I appreciate the reply.
Bill Norris
Back in the Day
The concentricity gauge comes in handy for checking a new die when first setting it up but it's useless for measuring case necks and loaded rounds. Never seen a difference in groups by using it. Test have shown up to .015 difference in runout had no affect on group size.
snert
Silver $$ Contributor
You should save your money and buy Alka Selzer instead.
I once read to lay in a big supply of Tums with the purchase of a concentricity gauge.
tharger
Silver $$ Contributor
.015 is a lot of runout
I built one years ago.
I found when I started using decent brass and decent dies it wasn’t necessary.
What was revealing was the amount of runout on factory ammo!
Bill Norris
Back in the Day
It is quite a bit but Alex Wheeler spoke about this sometime back and I think there is merit to his assumption. When the round is placed in a chamber (well machined chamber) there is very little room for a crooked round to fit into. If there is in some cases only a thousandth of play room just how crooked can a round remain after placed in that straight area?
I agree. If you want accuracy buy a quality name brand barrel. I have always bought Kreiger barrels. I have a factory Rem 700 BDL 6BR and a Rem ADL 6BRX with a tupper ware stock. They both easily shoot under .400" with good bullets. The gun can only shoot as good as the barrel no matter how much you tinker with reloads.
That was on believe the target interview. Fclass john also did a video where he deliberately cocks the bullet sideway enough it is clearly visible on video. It didn't really make much difference on target.
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