Hi,
I use the NECO "CONCENTRICITY, WALL THICKNESS AND RUNOUT GAUGE", which can be found here:
http://www.neconos.com/details.htm
I've found the gauge to be very easy and accurate to use, it's a little pricey though.
There might be other solutions to your problem, look around....
All the best,
Jeff
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Also referred to as "The Case Gauge," this item is designed to measure:
1) The curved "banana" shape of the cartridge case;
2) The relative wall thickness variation of a cartridge case;
3) The cartridge case head out-of-squareness;
4) Individual Bullets - out-of-round "egg shape" and/or
curved "banana" shape (excepting very small bullets);
5) The seated bullet and cartridge runout of loaded rounds. The accuracy of any firearm is determined -- and limited -- by the quality of the ammunition shot in it. The effect of imperfections in ammunition is cumulative; each flaw adds to the influence of all others. Precision shooters spend much time and effort "uniforming" cartridge cases, using advanced techniques to eliminate variation. Yet until recently, one of the most important of these variations has not been susceptible to detection by any device readily available to marksmen.
Normal manufacturing tolerances cause brass cartridge cases to vary in wall thickness around the circumference of their bodies. Under the stress of firing, a case with such variation stretches more readily along its thin side, transferring more pressure to the bolt face at that point and introducing an unbalanced force which contributes to bolt whip and vibration of the barreled action in its bedding. This whip and vibration varies from one shot to the next as cartridges are fired with their thin sides randomly oriented at different angles, causing reduced accuracy. The problem is made even worse if the brass is too hard or springy to completely fireform to the shape of the chamber, in which event the greater stretching of the case's thin side will cause it to develop a curve along the length of its body. These "banana" cases cannot hold a bullet aligned with and centered in the bore, undercutting the effectiveness of the handloader's careful case preparation.
Fortunately the accuracy problems caused by wall-thickness variation can be minimized, or perhaps eliminated, if all cases are "indexed" -- fired with their thin sides always oriented the same direction in the chamber. This causes bolt whip to be minimized and consistent, and, while bullets will still be misaligned, they will all be misaligned the same way, which often produces accuracy like that of perfectly aligned and concentric ammunition.
All we need to index cases is a means of accurately locating each case's thinnest point. This is not possible with traditional micrometers or other measuring devices used by handloaders.
The patented NECO Concentricity, Wall Thickness and Runout Gauge™ is a unique tool. In addition to permitting all the runout measurements possible with other concentricity checkers, it features a "chord anvil" fixture which allows the handloader to measure the wall thickness of cartridge cases, to determine its uniformity, and to precisely locate the thickest or thinnest point in each case. Brass can then be sorted according to uniformity, and permanently marked for indexing.
Until the advent of this new NECO gauge, indexing and checking for straightness procedures have been neglected because of the difficulty of the necessary measurements, but are now very easy to perform. Several large commercial ammunition manufacturers have adopted the NECO gauge as a standard laboratory tool for quality control purposes.
The NECO Concentricity, Wall Thickness and Runout Gauge™ is hand- assembled to precise tolerances from stainless-steel and hard-anodized aluminum components. It is equipped with a very high quality GEM Model #222A all-angle dial indicator and comes standard with two removable guides for bullet tips, two "step cones" for empty cases, a "chord anvil" for case-wall measurements, 2 double-sided V-blocks, convenient storage of accessories in the tool's base, and a thorough Instruction Manual. This Instruction Manual explains in detail the "why and how" of cartridge-case-indexing and other desired operations.
The GEM 222A is an auto reversing test style dial indicator with a large easy to read face with .001 inch graduations and can be easily read to .0005 inch.
The Gauge will handle .22- to .50 BMG. cartridge cases,and an additional chord anvil to accommodate .50 Cal BMG cartridges. A .17 caliber chord anvil is available at a small extra cost.
The Concentricity, Wall Thickness and Runout Gauge™ is also available from Sinclair International, In
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