My routine for concentricity and neck tension.

[ohiohunter]

I checked my neck tension, and by running the case through the die with no expander, I am around .009" neck tension. I don't have a mic so that measurement could be slightly off.

This is because I shoot the CEB bullets which are 0.0078 undersize.
With a Matchking, Id be at .016" if I size using the expander, as you usually would,

The rifle shoot much better this way, I'll see what happens in a side my side trial.

You don't need a mic.

Measure diameter of loaded round - bullet diameter = wall thickness.
Measure sized brass - wall thickness= inside diameter
Bullet diameter - inside diameter= Neck tension.

I have noticed the my 284win norma brass necks are THICK. Thicker than any brass I've used including RWS and Lapua. So thick I cannot size it in my FL BR forster die. So far I've smashed 2, I may have to turn down my necks. I also cannot put a bullet into a fired case neck.

 

[tbrice23]

You don't need a mic.

Measure diameter of loaded round - bullet diameter = wall thickness.
Measure sized brass - wall thickness= inside diameter
Bullet diameter - inside diameter= Neck tension.

I have noticed the my 284win norma brass necks are THICK. Thicker than any brass I've used including RWS and Lapua. So thick I cannot size it in my FL BR forster die. So far I've smashed 2, I may have to turn down my necks. I also cannot put a bullet into a fired case neck.

Yes you need to turn.

 

[Rack]

Ohiohunter
How thick is the norma brass compared to the others ?

 

[ohiohunter]

I only loaded and shot a few rounds but I never measured the diameter. With the tips of my calipers they look to be close to 0.020

 

[Rack]

That got me thinking that maybe thicker brass might be helpful in factory chambers to help guide the bullet .Remington and Winchester brass are about 14 to 15 thousandth.

 

[ohiohunter]

Possible for fresh brass but a partial neck size will allow the unsized portion of the neck to center the bore.

 

[tbrice23]

That got me thinking that maybe thicker brass might be helpful in factory chambers to help guide the bullet .Remington and Winchester brass are about 14 to 15 thousandth.

Much Thicker necks make for too much neck tension if you are using conventional sizing dies.
If you are using bushing dies and have thick necks with .004" clearance in your chamber with a loaded round ,than it 'could' be possible to get better precision .

 

[Rack]

Ok thanks that's good to know.

 

[BountyHunter]

Stainless steel media is good to super clean but it tends to make uniform seating difficult.

To help that use the graphite powder on the neck insides and you will see more uniform tension while seating.

I use a 21st century arbor press and can measure it precisely.

 

[918v]

I spin a bronze brush inside the neck for a sec or two and it clears up any seating pressure variance.

 

[EXPRESS]

I have done that in the past, and found it to be a good way to polish the inside of the necks.
I chuck a bronze brush in the last, and let it collect some 1000grit steel wool, give an even nicer finish.

 

[tbrice23]

You guys are better off leaving carbon in your necks!

Bounty hunter said he uses graphite , I personally use mica as a dry lubricant .
The only reason I dry lube my necks is because I sonic clean my brass and it leaves the necks too clean.