Neck Tension ES SD and Precision

[6BRinNZ]

What are peoples experience with neck tension? Would it be considered a large influencer on ES SD and precision or more in the fine tune category?
This is for 200grn bullets in a .308
Generally I run ~ .002 "tension" but I have a bullet thats not responding to my normal tuning techniques.
I've got it down from 2 moa groups to 3/4moa and looking for next steps to tighten it up.

 

[KMart]

Most of my stuff runs just fine at .001. To find out, you will have to test at .001, .002, and .003.

From time to time, the Daily Bulletin will publish some reloading tips from the USAMU. One of them was on neck tension. They said that for them, groups have a tendency to open up a lot after .003.

Then there are other variables such as how much bullet do you have in the neck at each neck size. Test test test.

 

[6BRinNZ]

Thanks
These bullets are very slightly on the skinny side and have a very short bearing surface. I was wondering if a touch more tension might be the right way to go to shrink the groups.