Originally Posted by JonM
the charge weights and bullet weights in factory ammo even the "match" ammo isnt very good with the noted exception of black hills match. concentricity is the least issue that makes ammo accurate.
if your a bench rest shooter you might see some benefit by segregating bullets but in all honesty its a waste of time in anything but extreme precision shooting where its all about the mechanical accuracy with little to no human factor
You'd be surprised at how non-concentric even "quality" ammunition is. I have a concentricity gage, and if I'm shooting for precision, run every loaded round through it.
Some of the factory ammunition is up to 0.009 out. The problem is the round-to-round change that can be as much as 0.0015 to 0.009 with everything in between. In 20 rounds I measured 2 that were 0.0015, 10 that were 0.005, 4 that were 0.007, 3 that were 0.008 to 0.009 and one that was 0.006.
You can straighten the bullet/neck area of loaded ammunition using the Hornady concentricity gage - and it helps. After tweaking in the concentricity gage - the 20 round are all 0.0015 to 0.002.
I started checking this because I have a rifle that will shoot under 0.5 MOA.
I was getting <0.5 MOA on 3 out of 5 rounds and couldn't believe I was pulling the other two and opening up the group. After straightening 20 rounds and testing, I was averaging right at 0.25 MOA.