Neck turning question.

[GregP42]

Hey guys,

I just made up a bunch of 6mm-284 by necking down some 284 brass. This has left me with brass that even without a round loaded into it is .273 diameter, what I am wondering is how much should I turn down the outside? I am thinking that maybe I should shoot for a .012 or .013 thick neck maybe? Right now it is about .018 thick. Anyone have any thoughts on just how much it should be?

Thanks,
Greg

[Lone Star]

The neck thickness is not that important, it really depends on the chamber neck diameter.  You will want to have between 0.002 and 0.004" of radial clearance between the loaded cartridge and the chamber neck.  The tighter the better for accuracy - but too tight and safety and practicality will be affected. 

How do you tell the chamber neck diameter?  Either make a chamber cast with a product like Cerrosafe (best), or turn the neck down on a couple cases to perhaps 0.013" thick, load and shoot them.  Measure the fired neck diameter and adjust the neck thickness to have a loaded neck diameter no larger than this dimension.  This will get you close at least.

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[GregP42]

Thanks Lone Star,

I was thinking about the chamber cast, just have to order up some cerrosafe to do it. IF and that is a big word, it is cut to the standard is should be a .272 neck in the chamber, I will find out when I cast it. I just wasn't sure how much clearance it should have, I have read to turn them so they are .269 with a bullet seated to expand the neck, but wanted a second opinion before I turned them all down.

Greg

[Drilling Man]

  You want the necks so a bullet will just go through a "fired" unsized case without resistance...

  DM

[gypsyman]

I neck turned 200 6mm Rem cases this last fall.  Barrel is in 6mm Rem.Imp. I didn't buy any factory ammo, just brass to reload. I could not get a brand new empty brass to chamber. I even told the barrel maker(aftermarket guy for T/C's) that I didn't want a tight neck. Went thru this years ago with a 219 Donaldson Wasp. But I got one any way,(tight neck that is). So I ended up turning 3 case's to .012 and trying them. That didn't work, so turned them to .010, and finally got them to chamber. And the bullet push's thru a fired case. Making a chamber cast would diffently speed things up. Good luck!! We keep trying peace, it usually doesn't work!! Remember-(12/7/41)-(9/11/01) gypsyman

[dave375hh]

I made my 6-284 cases from Norma 6.5-284 brass and ended up with necks at .014. My chamber dosen't have a tight neck at my request. This worked fine for me because the norma brass didn't require turning. 293 of 300 had a neck runout of .001 or less, so no need to turn them. I guess that's why the Norma brass was $61.00 per 100. It's really good stuff. I did 200 Win cases and had to turn them all to get them uniform, also at .014

[GregP42]

Thanks guys for the info, it gives me several things to check out. The Win 284 after necking down to 6mm has a neck that is .019 to .020 thick, but I have to say unlike what most people say I only lost two pieces of brass when I resized it all, and they were due to me mostly. I am waiting for the cerrosafe to get here and I will do a cast and figure out how tight or loose the neck is on the rifle.

Thanks again for all the help and ideas,
Greg