neck clearance for hunting rifle

GW Hunter

Well-Known Member
Joined
May 2, 2015
Messages
389
Location
Orangevale, Ca
Finally broke down and bought a PMA neck turning system due to the crazy thickness of Peterson 280AI brass. So what would be the optimum clearance for a hunting rifle? I was thinking 3 thousandths... Too tight? My cartridge length fits the magazine. It is not a 1 shot load load through the breech rifle.
 

MagnumManiac

Well-Known Member
Joined
Feb 25, 2008
Messages
3,273
Depending on throat design, it should be looked at like this.
Absolute MINIMUM CLEARANCE IS .003”, regardless if custom, semi custom or factory. If a carbon ring develops due to throat design, then this tight clearance WILL pose problems.
I have my reamers ground for a .004” clearance and choose my brass accordingly. I have a few turn neck chambers and I still keep that .004” buffer.
I also reduce the clearance on all reamers from .040” at chamber end back to .020” max or .015” minimum. This reduces the chance of carbon rings due to keeping the brass long. Have 2 A191 chambers in 300WM that have the chamber end only .010” over max brass length, not trim length. This seems to work very well for me.

SAAMI chambers generally have between .005” and .008”. Most I have measured were around .006” with the occasional .005” thrown in. This is ample neck clearance.

Cheers.
 

Rardoin

Well-Known Member
Joined
Jul 22, 2020
Messages
229
Location
South Louisiana
On my 6.5's and under I use 0.003" MINIMUM and am ok with 0.005" if the charge seals the neck and I get no carbon on the shoulder. In my 7mm's I use 0.005". Trying for minimal clearance provides no gain and can cause pressure irregularities. More clearance only becomes an issue if the necks are not sealing.
 
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