Neck Tension Question

[fx77]

Assume my loaded case neck is .266 and I want to add .002 neck tension to non turned brass case...with a .264 Neck die Bushing..
The loaded case is .266..
Then Suppose I choose a bushing of .263 which adds .003 neck tension, and I load the same bullet to final diameter of .266.

Except for maybe overworking the brass by .001 , what difference would it make for a constant powder load, atmospheric conditions, and rifle combination?

Thanks for your experienced opinion

 

[Dusty Stevens]

Just gonna build a tad more pressure

 

[Mozella]

The other consideration to selecting bushings is that they often don't result in "exactly" the desired neck dia after re-sizing, (i.e. a .237" bushing might actually give you .2375" or .2365") so having a couple different sizes in the right range is not a bad idea. In your example, maybe .263"/.264" and possibly .262" or .265". That way, you'll have everything covered.

You're correct and annealing has something to do with this kind of variation. That's why I anneal every time using a cheap, fast, accurate, and easy to use home-brew "Skip" style annealing machine.

 

[LCazador]

You're right in assuming that the .263" bushing will work. But that's all depending on how much spring back you get out your brass and what your chamber dimensions are. Let just say your chamber is .270" and your .266 loaded diameter springs out to .268" after firing( this is the diameter that is going into your bushing), you should be at .264" after sizing so that will give you two thousands neck tension. So it's a trial and error thing, fireform then measure then size and measure again. The difference between the fireform size and the sizing is your bullet tension. Your loaded diameter is not going to show nothing but the thickness of the brass and the bullet diameter. Another thing is brass spring back is dependent on what type of brass, how many times it's been loaded, and if you anneal it, that introduces a new variable( although more consistent) to the picture. So it's all about experimenting and trying it in your rifle. What works in mine is not necessarily going to be the same in yours!

 

[SS427]

All I care about is on-target results. Try it. If it shoots better, I don't care about over-working the brass (within reason, but even then...).