284 Win bushing.

Discussion in 'Reloading' started by barnesuser28, Nov 24, 2012.

  1. barnesuser28

    barnesuser28 Well-Known Member

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    Can anyone tell me what size redding neck bushing i need to order when using necked up Lapua 6.5x284 to have .003 neck tension? I dont have any brass yet and i am planning on ordering all my supplies at the same time.

    Riley
     
  2. barnesuser28

    barnesuser28 Well-Known Member

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    anyone?
     

  3. SBruce

    SBruce Well-Known Member

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    I dont shoot a 7mm so I cant expand a neck and give you an exact number, but I can get you close, assuming you're using brass that is similar neck thickness as mine.

    My 6.5-284 Lapua brass is averaging about .015" thick. Necking up will probably thin them by about .0005, I say this because when downsizing from 308 to 277, I gain .001 and when downsizing from 6.5 to 6mm I gain about 1/2 thou.

    Lets just assume for a minute that your expanded necks will average ~.0145"
    That's .029" of neck, plus the bullet of .284 should give a loaded round of .313" on the neck diameter....................I would order a .312, .311, .310, and .309 to start with. Use whichever one gives the best measurements and least runout once you've got everything in hand. But still tight enough that bullets don't move under recoil or when chambering the round.

    Also remember, that not all bullets will be exactly .2840" diameter. Some brands may be .0005 bigger or smaller. I've seen this in many other calibers, don't have any reason to think 7mm would be any different. That's just one more reason to order more bushings then you think you'll need, just in case.
    Also, if someday you decide to use Norma brass, it may or may not be the same neck thickness as Lapua. Or if you decide down the road to turn the high spots off the necks, the .309 will be tight enough to still give good tension.

    Hope this helps.
     
    Last edited: Nov 26, 2012
  4. Outlaw6.0

    Outlaw6.0 Well-Known Member

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    Well stated Shane. I am using a .312 in my 7saum, in your case, I would also recommend the .310 & .309. Without having the brass on hand, it's a crap shoot at this point.


    t
     
  5. barnesuser28

    barnesuser28 Well-Known Member

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    i think i will go with the 309 bushing, should give me enough tension evenif my lot of brass is a little off, this will be a repeater so enough tension is important.

    Thanks, Riley
     
  6. SBruce

    SBruce Well-Known Member

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    You should certainly have enough tension with the 309.

    There is however a downside to too much tension. Or too much working of the brass perhaps is the better wording. With a no-turn saami max. chamber, your brass will expand .004 or .005 upon firing and then necked down possibly . 008 or .010 with the 309, and then "necked up" by the bullet seating into it again by another .004 or .005. This doesn't really hurt anything, except it will eventually work harden your case necks prematurely, causing the need to anneal or replace cases for best precision and accuracy. Lapua cases arent cheap, I wouldn't want to replace them prematurely.

    Too much tension often also leads to excessive and unnecessary runout on loaded rounds, which can then induce less accuracy...........Goods and Bads in all decisions unfortunately.
     
  7. barnesuser28

    barnesuser28 Well-Known Member

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    I will be annealing the necks probably every 3rd firing, i will contact my gunsmith and ask what the neck diameter of his reamer is. I didnt know that excess neck tension can cause runout problems so i think i will go with the 310, not that it will make a huge difference.
     
  8. SBruce

    SBruce Well-Known Member

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    I've got .294 loaded rounds in my 6.5-284. I started off using a .292 bushing and found I got less runout by using the .293. I've seen this in some other cartridges too. IMO, so long as we keep TIR to .003 or less we'll never see the difference on a target. But when it starts getting over .006 we can expect accuracy issues, especially with tight neck guns.

    If you're going to anneal every 3rd firing, then work hardening your necks shouldn't be a concern IMO, even with excessive sizing.
     
  9. barnesuser28

    barnesuser28 Well-Known Member

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    I have the hornady concentricity guage so i can straighten the loaded rounds to .003 or less if need be.

    Thanks for your help!

    Riley
     
  10. SBruce

    SBruce Well-Known Member

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    You're welcome, Good Luck.
     
  11. barnesuser28

    barnesuser28 Well-Known Member

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    Thanks, im gonna need it! My donor rifle should be here thursday! Tha off to the smith for a rebarrel. You need a SS savage 22'' 270 win barrel?:D
     
  12. SBruce

    SBruce Well-Known Member

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    LOL, no not really. I just bought a 270 caliber blank last week.
    Post us some pictures when you get your new 284 build finished.
     
  13. barnesuser28

    barnesuser28 Well-Known Member

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    Will do! gun)
     
  14. barnesuser28

    barnesuser28 Well-Known Member

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    You guys were right on!! .313 loaded diameter, 310 bushing would be perfect, i would know for sure if they were perfect if Midway knew the difference between $89 6.5x284 dies and $210 284 win dies :rolleyes:.