question on tight neck chambers

Discussion in 'Reloading' started by B Jordan, Apr 12, 2006.

  1. B Jordan

    B Jordan Well-Known Member

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    on a 6mmbr .262 neck what would the neck measurement be of the loaded round? and what redding neck size bushing would be needed to resize it ? thanks,Brian
     
  2. EddieHarren

    EddieHarren Well-Known Member

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    Brian, depending on your rifles performance, I think .0085" neck wall thickness will do. That will give you .002" neck clearance. You should get a .256 and a .257 bushing. That being said, my PPC rifles with .262 necks, have always done better with .009" neck walls, sized with .258 buttons.
     

  3. B Jordan

    B Jordan Well-Known Member

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    [ QUOTE ]
    Brian, depending on your rifles performance, I think .0085" neck wall thickness will do. That will give you .002" neck clearance. You should get a .256 and a .257 bushing. That being said, my PPC rifles with .262 necks, have always done better with .009" neck walls, sized with .258 buttons.

    [/ QUOTE ]

    i have read some where that for a bolt action rifle you want .002-.004 neck tension is this the same thing only .009 ? thanks for your help ,Brian
     
  4. Bart B

    Bart B Well-Known Member

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    Folks using tight chamber necks typically like their loaded round neck diameter to be between .001 to .003-inch smaller than the chamber neck diameter. It depends on what they get best accuracy with.

    Interesting thing is that many people get equal accuracy with normal chamber neck diameters and loaded round neck diameter being .004- to .006-inch smaller.

    Whatever the diameter of your loaded round neck diameter is, use a die .001- to .002-inch smaller. This depends on how much tension your want on the bullet and how much elasticity the brass has to spring back.
     
  5. Varmint Hunter

    Varmint Hunter Well-Known Member

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    [ QUOTE ]
    i have read some where that for a bolt action rifle you want .002-.004 neck tension is this the same thing only .009 ? thanks for your help ,Brian

    [/ QUOTE ]

    NO - The .009" reference is the neck wall thickness, presumably after neck turning. The .002-.004" is a reference to how much smaller the neck diameter is (after sizing) compared to what it will be when the bullet is seated. This measurement is often called " neck tension".

    Generally speaking, with a .262" neck you would want (aprox) a loaded round neck diameter of .260", thus leaving .002" of neck clearance for bullet release. To get a loaded round neck diameter of .260" you must subtract the actual bullet diameter of .243", which leaves .017" for the brass tubing itself. Since the neck is on each side of the bullet you divide the .017" by 2. This will give you .0085" for the neck wall thickness.

    Last consideration - When determining the proper bushing for sizing you merely determine what your loaded round neck diameter will be and subtract (aprox) .003". This allows for .001" "spring-back" of the brass and leaves .002" neck tension.

    Bottom line for someone new to tight neck chambers:: Make certain of you chamber neck diameter before begining and carefully measure you finished handloads to make certain that they will fit in the chamber with adequate room for safe bullet bullet release. (Typically .002" or more even though some benchrest shooters will use slightly less).

    Hope this helps.
     
  6. BountyHunter

    BountyHunter Writers Guild

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    My only comment would be that I would not deliberately set up a BR with a .262 neck. that is very thin and only normally used on the PPC. The case necks are subject to damage very easily and no need for it.

    I would recommend that if you are ordering your reamer for a 6mmbr, look at some of the threads on this subject at www.6mmbr.com.

    Most are recommending that the 6mm BR either be a .271 no neck turn neck or at most .267-278.

    I just got a 6mm BR-DX (ack imp) reamer at .269 for new 600 yard gun.


    BH
     
  7. Guest

    Guest Guest

    You will be surprised at the performance of a 6mm improved when you get it built.I will push a 243ackly very hard.I have both and hope to do a article later when I get all the data together.
    Old Bear
     
  8. goodgrouper

    goodgrouper Well-Known Member

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    I would not recommend a 262 neck on a 6br if you are intending to use Lapua brass. I have a 6brimproved on a 265 neck which means my brass must be turned down to 263 and it is a nightmare making it that thin. Turning .004" of each side of the tough as nails Lapua brass was hell on equipment, nerves, and the clock.

    My other 6 br is a 269 neck and it is a breeze to make and shoots just as good.
     
  9. EddieHarren

    EddieHarren Well-Known Member

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    Goodgrouper, what kind of neck turner do you use? Normally, with a good sharp cutter, turning Lapua is like cutting butter.
     
  10. TracySes23

    TracySes23 Well-Known Member

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    Your post is exactly right! My tight necked chamber is .250" dia. tight necked 22-250. Turning to a .012" wall thickness gives .002" total clearance. I've neck turned Lapua, Remington & one other brand of brass & they have all cleaned up with a .012" wall.
    I can't imagine any brass that would need to be turned to a .009" wall in order to completely clean up with a perfect neck wall without any thin spots.
     
  11. 243winxb

    243winxb Well-Known Member

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    Very OLD Thread :rolleyes:
     
  12. Mikecr

    Mikecr Well-Known Member

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    For a .262 chamber neck, loaded neck diameters could measure .261 if chosen.
    In that example, the bushing .002" smaller(recommended) is .259".
    .262 is not very common with 6br.

    I get the feeling you don't understand this well enough though.
    Tight neck chambers are managed with more advanced reloading than common. You can tell by the sentiment in replies right here that some are afraid of tighter clearances, and/or advanced reloading.
    It's just not something you can take a big jump into with success.