neck turning

[ultimate_monkey]

so iv been neck turning for a while and i was in the loading room playing around tonight, and was measuring some brass, on almost all the cases (new untouched) the thin side was 10-11 thou and the thick was 14. and i got to wondering, i know its bad to turn the necks to thin but what is "to thin" ?? As in whats the thinnest a neck should be? on every thing iv turned so far, the thin sides been around 12.5-13 thou. the casings were in 308.

 

[b72471]

If you're turning necks for accuracy with a factory chambering. Clean up the necks to about 80% that's about it.
Bill

 

[yodave]

I run a 10 thou neck on a 30 caliber case..........my chamber reamer was set up that way.
It really depends on what your chamber is cut at, for a factory chamber or any chamber measure a fired case, if its 4 or 5 thou over a factory brass then turning is going to cause the brass on the neck to move more, it will work harden faster from all of that swell/shrink and eventually fail. 1 to 2 thou clearance is all that is required, in your factory chamber I doubt even skim turning is going to make any noticable difference in group size...YMMV

 

[ultimate_monkey]

yodave, thanks for the reply, i was curious as im mid build and while i wait for my barrel to show up was going to start looking at chamber reamers. was thinking when my lapua brass shows up i would neck turn it all to be identical but wasnt to sure how thin it would be ok to turn to, so if i turn it all to 10 or 11 thou i should be good to go as long as my reamer is ordered to match ?

 

[Mystic Precision]

Be more concerned about the alloy then a thou here and there. Some brass is very hard and not ductile. Others soft and very flexy. No way to know until you get the brass and shoot it.

In general, I strive for 12 thou as an average with 10 thou as a min. I anneal as often as necessary to keep neck splits at bay.

Overly tight necks is not good if this rifle will get dirty or see weather so it is a compromise. For F class or a hunting rifle, I want clearance (at least 3 thou per side). As long as fired cases don't split, I am happy. The amount of stretch is not important unless of course you get splits.

More is better then too little.

Jerry