Re: Looking for a concentricity gauge
What you are really doing with a run-out gauge is checking the capability of your reloading process: are the tools and technique adequate? If you are not shooting match, simply rolling your loaded rounds across a flat surface (glass) will suffice. Any wobble will tell if your rounds are over 0.002". If you can't see wobble, you're good to go. Rolling your sized brass will tell you if the necks are true.
The best tool for checking case-neck variation is a ball mic; cheap ones are available and will do fine for your purpose.
If you have to have a run-out gauge, the Sinclair "spinner thingy" is the most popular and easiest to use. Redding has a case neck gauge that uses a dial indicator (as does the Sinclair "spinner"). Recognize that if you get both, you need only one dial indicator. The case neck gauge is faster than the micrometer, but less accurate. If you're sorting all of your brass, it's convenient.
In the end, you're checking to see how good your brass (or sizing die) is and if your seating die is doing its job properly. To what extent is it necessary to go to in order to make these determinations? And since you're not turning case necks, all the case neck gauge (or ball micrometer) will tell you is if the brass you bought is up to snuff.
Haven't heard much good about either the RCBS or Forster run-out gauges. The NECO is expensive and has involved set-up, but is excellent otherwise.
Last edited by Winchester 69; 01-09-2009 at 05:22 PM.