Use of a dial indicator

[mikeinct]

I would like to test the concentricity of the reloads I make to shoot in my varmint rifles...using a small "V-Block" to hold the neck level to the dial indicator button..simply spin the loaded round & find out how true to center it is...Have any of u done this to try & improve groups...I'm neck turning some of my brass [ I have to in the .270 neck 6MMBR] I tried the neck turning & careful sorting with my 22-250 ..Not happening with that gun & factory chamber...The unturned ammo shoots better groups in that gun...Thats why I want to use the dial indicator to see before I shoot which are the best cases...Using the neck truing tool [a forster hand held] it was easy to see most of the remington cases I have been using have necks that vary in thickness from one side to the other...ie: no contact on part of the case neck to just barely shaving the other side..I tired doing the very minimum neck turning on those 22-250 remington cases ...my 6mmbr gun uses Lapua brass...anyone have the answar to this problem short of rebarreling the 22-250 gun??..mike in ct

 

[Hipshot]

Consider not only concentricity but also the neck turning you are doing that might affect accuracy. The diameter in the breach may not be right for neck turned brass.

I use an RCBS cartridge gage setup to check concentricity,among other things). Don't hold or spin the bullet at the neck, hold and spin from the body to the base and set the dial indicator at the bullet, where it exits the case, and also at the case neck.

If you have a problem it might be the seating die not handling your neck turned brass properly.

One other neat tool to have is a tube micrometer to check brass thickness around the neck of your cases.

 

[StephenPerry]

Case Concentricity
I have gone through the same process trying to improve my lot with 6 Rem cases. I gave up on commercial brass and started necking down GI 30-06 cases. This gave me a little more neck area to turn. Use a skim cut on nk turning it might cut on one side but not the other that's fine your cutting to get close to the axis anyway. Try and get a mandrel that has no wobble when inserted into the nk and slightly grease the area to be cut before cutting. Run a RCBS nylon brush inside the neck also before cutting. A RCBS .001 case spinner is all you need at this time. Set up to spin the body in front of the web area and again just behind the shoulder. You can read 1/2 thou on those gauges. A 1/2 thou to 1 1/2 thou will get it done.
Stephen Perry