Measuring brass neck thickness 7mm SAUM

[shooter83]

I'm about to neck turn some new brass (Remington), based in the thickness of some Norma brass that has been neck turned for a tight neck chamber. I measured me Norma brass with a seated bullet and subtracted the bullet diameter from the neck diameter and did the divide my two to get 12thou. Do I just trim the Remington brass to 12thou thickness? I don't have a tube micrometer so had to used standard calipers. 

What that's best way to do this? I'm guessing tube micrometer if I can get an imperial one somewhere.

Thank you 

[Leeman]

I've never bothered with a tube mic, just set up the turner so it skims the brass, re-size, seat a bullet, measure with standard mic or dial caliper.  If too thick, expand up and skim a bit more off.  I think getting them all the same is more important than the actual neck clearance, as long you you have some clearance and it's not too excessive.   Various rounds I shoot vary from .002 to .006 clearance and I don't think one is any better than the other.  A tube mic would be quicker measuring of course with less faff and if you have limited bushing size options, assuming you're using bushing dies, it would make it easier to match loaded rounds to the bushings you have available.

[No i deer]

I started off neck turning my saum brass using the digital calipers too measure neckwall thickness.!!

Just be fussy and measure a few times or as many times you want until your happy....

Just don't get the turner hot..!!

I use the the spray lube in a case tray..

Fill up 2 holes where the cases go in and dip the necks in before turning with the case in the shell holder in the cordless screwdriver..

Just don't rush through a 100 cases.

These days I have a sinclair neckwall thickness calipers..

They're just a tiny bit more accurate..

After using the sinclairs I thought I could of managed without them ok..

The calipers will be fine.

[gunner]

hi , id sacrifice 1 or 2 cases , set up the turner and don't take too much in a pass and like no i deer keep it cool not hot itl start to sort of gall or rough cut . once you think the brass is cut to your 12 ? thou seat a bullet in it  then re measure the overall . i assume your using an expander mandrill ? ill bet 1 or 2 of them case mouths will had a wee dent in . cutting depth of cut is also really important . there is an post on this very site about this that goes in to detail which id advise to read , it may be in the handloading section - named neck turning how to etc , i appreciate your not a beginner but its worth a look - some tips you may not know . all the best 

 

[No i deer]

I've not had a tight neck too 12 thousandths..

My 284 is 14

The saum is 13.5

7mm 270 is 13..

It's probaly best to turn in 2 stages..

Do them all at 13.5 then down too 12..

Make small adjustments as when the screwdriver spins it will cut more off than you think..

Don't cut too far into the shoulder either because after several firing the necks will snap off..

Approx 20 thousandths..

This is the hardest bit to get right using the K&M turner..

 

I shot with somebody a couple of weeks ago that had a neck snap off in the chamber..

He said the brass had only done 3 firings so I think he cut in too far..

I have some 284 brass thats done 15/16 firings and the necks started snapping off so I scraped them.

[shooter83]

Thanks for the advice all. I think my neck wall is about 12thou so neck snapping off is a real concern. But I am getting some real good SDs/ES. So I guess one has to compromise.

Once again a lovely gentleman off here has offered to lend me his tube mic. I won't go as far as to identify him. You know who you are. 😉

 I was so afraid to reload me first time, I had all me equipment, set up and sat there, but really wanted someone to show me the ropes 😂. Turns out this person was just a few minutes down the road. Came over and spent a good couple of hours showing me the ropes.

Since then has had to put up with me incessant questions. There are still some genuine, good people out there.

Thank you 

[No i deer]

There's plenty of good folk out there..

We all had too start somewhere and good advice is invaluable..

Its better too ask questions than make unnessasary mistakes..