Must read: whisper and headstamp
 

I mic all new headstamps that I make from 223/5.56 brass. Well today while trying new brass I discovered something that may be benificial to all. Hornady,PMC and rorg are all too large and need to be neck turned if used. Keep in mind that the neck diameter of my chamber is approx. .335. Here are some of the numbers I found from the brass I did today.
Win / RP / FC .325 - .330
Lake city/MAL .330-.332
hornady .336
PMC/RORG .338 - .340
Hope this helps someone-
John

John-

I have not found FC brass to be as thin as you quoted.
I ran into problems with neck diameter.
My reamer measures 0.336" at the neck base and at the case mouth.
FC brass was running from about 0.330" at the case mouth up to about 0.337" at the base of the neck.
It's really just the "doughnut" that you have to watch for.
People who neck-turn will know of what I speak about...

Switching to RP brass has solved all these problems for me.
I am seeing 0.330" at the case mouth up to about 0.332" at the neck base.

Randall Rausch
www.ar15barrels.com