Home Forums Hunting & Shooting Ask The Gunwriters Run out, concentricity and gauges

I am just getting a Nico TIR gauge but I was doing some reading and one author said that any gauge relying on V-blocks or bearings on the case is going to exaggerate run out as it is introducing the eccentricity of the case. This person seemed to think that the types that supported the cartridge at the base and bullet were giving a more accurate picture of the run out and mimicked how the cartridge is supported in the rifle chamber (by the rim or base and bullet). The H&H and Hornaday support the case this way.

So have a taken a step backward going from the Hornaday to the NICO? If this is correct should I be gauging the case necks rather than the bullets?

I am mostly of the school that believes in loading them straight to begin with and then don't worry about it. I think either gauge will be useful for checking die set up. Thoughts and advice?

don't think it matters, .000 is .000. It may matter more on new brass but unless your chamber is messed up, once it is fired all should be good

You mean Neco like this one?

A lot of chambers are far from perfect, but I do test "runout' on the body of fired brass to see how round the chamber is. Usually there is very little, less than .001, more often .around 0001. It is equally likely the bolt face isn't perfectly square to the chamber, and the gauges that index off the base and bullet will show runout induced by that situation.

Gauges that index using the bullet can't be used to measure concentricity of the brass BEFORE seating the bullet.

Here's what you can do with the V-block style of gauge, mathman covered it well:

DBoston,

From your post it seems the "somebody" you mentioned doesn't think supporting the case at the shoulder matters, but don't know for sure if that's what you mean.

At one time I compared run-out on the same cartridges with four different gauges from Hornady, NECO, RCBS and Sinclair, measuring all the bullets .1 inch in front of the case mouth. All provided exactly the same reading.

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YES

MD thanks

I think I'll like the NECO gauge better and it wasn't an unwise purchase.

What I was trying to say is that when the case is rotated on V-blocks or bearings it exaggerates the TIR by including any warping or eccentricity of the body of the case. not just the bullet and/or case neck alignment. Interesting that all the different gauges gave essentially the same result, that is reassuring.

Sounds like you have a good handle on the understanding of TIR and the tools needed to check it. You are also right about loading straight ammo from the start. Some guys will argue and say the v-block system is the best, but let them think that. The one I use supports the bullet and the case head/rim of the cartridge and works very well. I'm not saying it's the best, just that it works just fine. The important thing is you are checking your loaded ammo and adjusting dies accordingly to minimize run-out.

The hornady run out gauge/cartridge straightener lacks the fundamentals to give reliable run-out readings 100% of the time.

You have taken a step ahead DBoston.

NAGW, but I have and use the Hornady model. Granted, I can’t check runout of the case without the seated bullet installed. But my findings are thus; with the bullet seated, I check for runout on the case neck just behind the case mouth. If straight at this point I move the indicator out on the ogive of the bullet and check runout again. If the neck is not straight, I use the straightener to straighten the neck, then again move the indicator to the bullet and check runout again. In both instances, if the neck is straight, so is the bullet. This may not be the best way to accomplish what I’m attempting to gain but it works for me. And my handloads seem to shoot extremely well once I have settled on a load for my rifles.

Thanks all looking forward to getting the new gauge. I will check more with this one. One question I have is do any cases come out warped from the factory. Most of the new brass I have is Lapua, Nosler and Norma so I doubt these would be off much, but I do have a couple of lots of PPU I will check before firing.

Yes they can.

DBoston,

Mathman is correct--but even "lop-sided" new brass (meaning one side is thicker than the other) tends to measure pretty straight, because the final forming die at the factory does not have an expander ball. But it sure can become a "banana" after the first firing.

I've even had it go the other way. A while back I bought some commercially branded bags of new LC15 brass, American Eagle I think. They weren't super straight, and they didn't assemble into cartridges that were all that straight. After the first firing they turned out to be really good with good necks and no problems sizing straight or being assembled into straight cartridges.

DBoston: I have been using the NECO tool/gauge for a LONG time now and heartily recommend it to you.
It does a LOT of things VERY well!
Including helping me make more "accurate" ammunition.
Good luck - learn that tool and all it does - it will pay for itself soon enough.
Hold into the wind
VarmintGuy