Neck Turning Question

[tourguide]

I have a 8mm REM mag case, and I'm try to figure out the minimum case wall thickness when turning it down. What do you think the minimum thickness can be before something bad happens?????

Do you think the best method of neck turning is outside or inside? It's a 8mm necked down to 30cal. So the case gets resized, I have been turning only fireformed brass after resizing.

How much variance of wall thinkness do you think you should see?

Thanks for the help.

 

[Coyoter]

First off, I wouldn't recommend neck turning unless you've got a tight chamber or at the very least are planning on using a bushing competition neck die. If you've got a custom tight chamber then you'll want to turn your brass to .0015" - .002" smaller than your chamber. I wouldn't go smaller than .012" neck thickness if I could avoid it, and definately no smaller than .010" or you'll start tearing case necks as you turn. Generally speaking, you'd buy some (good) brass, see how much outside neck turning it takes to clean it up with about a 10% cull rate, seat a bullet into it, measure the neck diameter and order a barrel .002" larger. Most of us get the barrel first and adapt, so don't feel bad if that's what you did.
I'm sure most of the folks on this board will recomend the Sinclair outside neck turning tool. It's very precise, but slow. Personally, I like the Forster case trimmer with the outside neck turning attachment. You can hook it to a Skill Twist or similar power screwdriver and save yourself hours of hand cramps. The Forster is very precise if you do your part in setup, and is similar in price to the Sinclair tool if you already own the screwdriver.
Good Shooting, Coyoter