Expected concentricity out of new Lapua brass

[rmercado]

Hi all,

Before I tear my process apart, what is the expected concentricity I can achieve with this setup? Hornady L-N-L classic press, Redding micrometer seating die (upgraded from RCBS Comp). Using virgin Lapua .308 brass, and 175 SMK's.

My baseline is FGMM brass (fire formed), 175 SMK's, and RCBS Comp seating die. I was getting (out of 50), less than 10 at 0.001, most at 0.002 and 0.003, and 10 or so between 0.004-0.007. I'm using a Sinclair concentricity gage. My necks come out between 0.001 - 0.002 using a Lee Collet die.

Virgin Lapua brass neck concentricty is anywhere between 0.001 - 0.004. Other than inside/outside chamfer, I have not worked the brass. I reloaded 50 and most are coming in between 0.003-0.004 with a few at 0.002 and more than normal between 0.005-0.007.

Should I be concerned? I have 450 pieces of new brass to go, and would like to get the best out of my first loadings... any suggestions on changes to my process? Neck size them? Expander die? Anything else?

Thanks in advance.

 

[groovinpickle]

Re: Expected concentricity out of new Lapua brass

I sorted 500 pieces of new .223 Lapua by neck concentricity earlier this year, and only had 5-10 that were above 0.0025" as measured on my Sinclair gauge. And I think those topped out around 0.003". I don't think you can directly compare my measurements to yours, but in my experience I haven't noticed problems with concentricity of Lapua out of the box.

This may be obvious, but are the necks at all out-of-round from shipping? Minor issues that can be ironed out with a light touch from an expander die will throw off a neck concentricity measurement.

 

[rmercado]

Re: Expected concentricity out of new Lapua brass

Groovin, I'm also using the Sinclair tool. My necks aren't dinged up, but I did find plenty of them really tight. Wouldn't even go into the pilot on my Forster trimmer. Looks like I'm going to have to expand them anyway.

How did your bullet runout measure on the first loading? What seating die are you using? Maybe I'm over thinking this and should just shoot them and worry about concentricity and neck tension in the second re-load.

 

[Leaddog]

Re: Expected concentricity out of new Lapua brass

You have to fire form them and full length resize before you can get to where you want to be.

 

[rmercado]

Re: Expected concentricity out of new Lapua brass

Yup, I'll get lots of trigger time fire forming, so all is not a waste. My expectation for "minimal" runout should not be based on virgin brass, I get that. Just wanted to review other thoughts and opinions.

I plan on running the remainder through the expander die to help with neck tension. Any other prep for Lapua brass before loading them up? Thanks for the responses.

 

[MALLARD]

Re: Expected concentricity out of new Lapua brass

i get about 20 good lapua cases out of 100

 

[azimutha]

Re: Expected concentricity out of new Lapua brass

On the first firing cycle, I just do the same that I do for all my loading - measure each charge to the 1/10th grain (and probably a little better than that because if the scale isn't right on the hash mark I'll dump a few kernels and trickle again). It's all Lapua from the same lot so not much variation. ES and SD go down a bit on later firings.