How much clearance

[canuck]

For you guys with a turn neck 7mm saum..how much clearance did you need to get optimum accuracy?
thanks in advance for your input

 

[Preacher]

Mine has a .316 neck and I turn the brass to .0138...
It shoots really nice at 350 yards here at home, and most always under a inch..
I normally use the 162 Amax, but it will shoot the 120 Nosler BT's good enough for groundhogs out a ways............

 

[canuck]

So I take it your loaded round measures .3138 ...is that correct?
I was asking cause I suspect I am a little to tight. Mine is a 0.315 neck with a loaded round measuring 0.3135 . I am just starting load developement now but I think I will take a little more off my necks.
out of curiousity what load are you using for the 162 amax?
thanks for your help..

 

[Preacher]

58.6 = RL-17 shot good with the 162's I can go higher but saw no need after I did..
My loaded rounds are .311 and the empty case makes a pop sound when I pull a bullet back out of it....

 

[canuck]

In your opinion am I running a little too tight or is it ok? What do you think is acceptable clearance for an f-class chambered in this cartridge?
thanks again for your input

 

[Preacher]

If a bullet your using won't go back in the fired case with little if any pressure your to tight.... When I have a case perfectly trimmed to fit, a bullet pushed into a fired case
will push right back out a little because of the air pressure in the case........

 

[blackbrush]

I like your method of determining case neck thickness...which leads me to my next questions;

1.) do you vary your neck sizing bushing, therefore tension?

or

2.) do you work with same bushing and vary neck thickness?

3.) Is less neck tension necessarily better?

 

[Octopus]

A little extra clearance never hurts. Too little clearance can cause major problems. Better to be on the safe side.

If you load with a Jam. That is with the bullet into the lands the neck tension will not be an item in the equation for precision.

If you are shooting with a jump then the neck tension needs to be consistence.

 

[CoverDog]

So I take it your loaded round measures .3138 ...is that correct?

If my math is right that is incorrect. .0138 x 2 = .0276 + .284" = .3116 Subtract that from his neck chamber measurement of .316 should leave a clearence of .0044