neck concentricity

[snbend]

I am having trouble sizing my brass. Same issue different calibers. I recently purchased a neck concentricity tool and found all of my necks are not concentric from .002 to .008. The brass is once fired. I checked before and after sizing. Sizing did reduce the variation but did not eliminate it. I tried spinning the case in the shell holder about 30 degrees and sizing again. Didnt help. I am using a forster co-ax press which is supposed to be self centering. The weakest link is probabaly the RCBS dies. I wouldnt mind spending some hard earned cash on higher quality dies but would like to know that would resolve the issue before slapping down the cash. With the elasticity of brass how do you get the brass back to center once it is off centered? Seems like it would spring back some regardless. Thanks for your help.

 

[billmo]

The fired brass coming straight out of the chamber before re-sizing should be almost perfect since it is formed to the chamber. The brass should not be showing much runout at all at that point. If you have .008 runout right out of the chamber that could be a problem. You may want to let somebody look at your chamber. Bill

 

[TheSilverFox]

I not shure i understand.

You check neck concentricity on a fired case,before resizing) and some have up to .008 runout?

 

[snbend]

There is .008 of travel on the dial indicator. I guess technically they are only out .004? They were not fired in my rifle. I bought them "once fired". I expected them to be concentric if fired. I have not turned the necks either so some of the variation may be from inconsistent neck thickness? I am new to checking concentricity so not sure if my approach is correct, or if my expectations are too high.

 

[billmo]

snbend, You are correct. You need some help here. If those cases were not fired in your rifle, then you need to FULL LENGTH resize them. Concentricity at this point means nothing.Check the brass over for defects. Full length size them, trim to length, and load them. Shoot them in your rifle and then check for concentricity to see if your chamber is straight. Now, at this point you are ready to start load development for your rifle. I personally like the Redding F/L bushing dies so that I can control neck tension and the Comp. seater die. If you go to Redding's web-site you can read about the dies and how to decide which bushing you need. How long have you been reloading? With that question answered a lot of these guys will probably jump in and help. We have to know what level basically that you are at with handloading. I hope this helps. Bill

 

[snbend]

Thanks for your reply Billmo, I have been reloading a long time, 30+ years, casually to customize a load for a hunting rifle. Recently though, I have developed an interest in long range shooting. I started by reading as much as I can find at sites like 6mmbr.com. I have found it is much easier to read about how to do it than it is to do it. I have limited funds so the right tools take time to acquire. I will be delivering a barrel, action, and stock to a gunsmith to build a 6.5-284 the weekend after next. When I get it back I will have to begin working on a load for it. In the meantime I took my bushmaster out and started working on some loads for it. Hence the concetricity issue. I have shot it since my earlier post and have checked the concentricity as you suggested. The brass is far better now than originally measured. Generally under .003 movement on the dial indicator. I guess I was expecting to be able to true the neck with the sizing dies. Due to the expected short barrel life on the 6.5-284 I was hoping to be able to make the brass concentric without having to fire form it. Any suggestions will be greatly appreciated.
Scott

 

[billmo]

Scott, I'm afraid you gonna have to shoot it to fireform that brass to your chamber. Then, take a look at it and see how close to perfect it is. Should see .002 or less with good brass. Then you can begin to work with it and get your powder right. Bill