Neck bushing sizer information needed

bpostbpost Member Posts: 30,918 ✭✭✭✭
In my NEW 6BR 8 Twist the fired brass has an outside diameter of .2675 to .2685 after firing. A bullet will slide into a fired case mouth with just a bit of clearance so the neck thickness is about right.

What size bushing do I need for proper neck tension?

I have a .259 and am afraid that is too tight for this application.



  • steve4102steve4102 Member Posts: 186 ✭✭✭
    edited November -1
    Measure the neck of a loaded case (not fired) and subtract the amount of desired neck tension. Redding recommends subtracting .001. I find that a little less neck tension than needed. Redding also recommends not to size the neck more than .005 with a single stroke. If you need to size more than .005 from a fire case you should use two or more bushings.
  • perry shooterperry shooter Member Posts: 17,390
    edited November -1
    Hello You most likely have loaded more 'Bench rest ' type cartridges the I have but . for starters I would go .243 + (2X the wall thickness of your case.) and then - .005 reason there will be some spring back in the brass after you size . I was hoping many others would answer your post so I would know if I had been doing it correctly. Cheers Karl
  • JustCJustC Member, Moderator Posts: 16,035 ******
    edited November -1
    drop back off the thickness of the brass x 2 + the bullet dia.

    lets say your brass is .012" thick after neck turning,..so a total of .024"

    your pill is .243" dia

    so .024" + .243" = .267"

    I usually go with 2 bushings from the start,..a .001" neck tension and a .002" neck tension bushing. These obviously would be the .266" and .265" bushing

    when you have to switch down .001" in bushing size to gain your accuracy back, your necks are hardening, and annealing is the next step other than throwing the brass away and starting over. With the BR case, you can quite likely use 1 batch of brass until the throat is toasted,..so annealing is the answer then.
  • juddroyjuddroy Member Posts: 204 ✭✭✭
    edited November -1
    You should mic the LOADED round and subtract 2-3 thousandths.Only size half way down.After 3 firings you will be fireformed and the unsized part of the neck will really help center things up.
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