Twice turned brass finally shot

[bikemutt]

Life has twists that keep me from shooting, but, I'm persistent darn it 

I shot the brass I'd posted about previously; necks outside and inside turned to 12.5 thou wall thickness. These necks look pretty clean which isn't too far off from how the last batch of outside turned necks looked when they were first fired; they were turned to the same wall thickness, 12.5 thou-ish.

The reason I'm posting this is I'm measuring the now-retired, 14x fired brass necks, they are averaging 11.7 to 12.0 or so neck wall thickness.

Do neck walls shrink in thickness as they're shot?

[LeadHammer]

Not sure, before I threw a bunch of Hornady 12x fired brass out, I felt like the necks were thinner, but never bothered to check. These were un-turned necks. I know I was loosing brass thickness at the case head separation area on mine and was trimming of OAL length of course. I'm going to measure and keep track of the necks on my Lapua.

[DHuffman]

When I refurb .011" turned BRA necks at 5-7 firings with the cutter set up to cut at .011" it rarely cuts much if any until it gets half to two thirds to the neck shoulder.

That makes me think they get thinner at the mouth but fatter at the neck shoulder junction.

That is probably a by product of bushing dies that don't size all the way down to the neck/shoulder I think.

[gman47564]

Chris are you using the same instrument to measure with as you did to start with.. I know you been doing alot of experiments with measuring devices?

[bikemutt]

Chris are you using the same instrument to measure with as you did to start with.. I know you been doing alot of experiments with measuring devices?

Grant, I did use the same micrometer when I turned both the OD-only and the ID/OD brass sets. that mic was not modified.

The modified mic indicates the ID/OD turned brass is 12.5 thou thick, as did the unmodified mic, this makes sense since both OD and ID turning were done on a trued mandrel and a trued socket-type mandrel respectively, I expected coaxiality.