Neck sizing 7mm

Discussion in 'The Ammo & Reloading Forum' started by hunte567, Nov 12, 2011.

  1. hunte567

    hunte567 New Member

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    I have the rcbs 2 die set for my 7mm. Im only want to neck size and not full length size my casing. How do I do this. Thanks
  2. myfriendis410

    myfriendis410 Member

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    Just back the sizing die off of the shellholder one full turn. That will allow you to size the neck but won't set the shoulder back.
  3. cpttango30

    cpttango30 Guest

    Don't you want to at least bump the shoulder a little?
  4. 312shooter

    312shooter Active Member

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  5. reynolds357

    reynolds357 Former Guest

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    If that actually worked, many of us sure have wasted a lot of money on neck sizers over the years. You can not size the entire neck that way.
  6. JLA

    JLA Well-Known Member

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    In most cases you dont need to size the neck all the way, just the majority of it. I back my FL die out to 'necksize' all the time. It works fine, and makes accurate ammo. And regarding the 'bumping' the shoulder.. Only when the bolt starts to not want to close freely. then ill adjust the die down until it slightly bumps the shoulder and solve the problem. It usually takes 3-4 cycles before the case stretches to that point tho, depending on the cartridge and rifle of course..

    Only time those specific competition grade necksizers are gonna do you any good is if youre shooting benchrest competition and trying to shave another .100" off a .290" group at 100 yds.. Most off the shelf hunting and varmint guns are MOA or just under, and will most likely shoot carefully loaded ammo the same no matter what dies reloaded them.
    Last edited: Nov 13, 2011
  7. myfriendis410

    myfriendis410 Member

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    In belted magnums what many often assume is an oversized shoulder can actually be attributed to the case being oversize just forward of the web. Your full length sizing die won't size that area and requires a special tool to size up to the belt.

    For hunting ammo I always full length size and make sure the case at the web is sized to factory dimensions.

    Like JLA said; you won't really see any benefit in a production rifle by neck sizing only. If you have a match chamber that is going to be a different animal entirely.
  8. howlnmad

    howlnmad Well-Known Member

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    As JLA said, you don't need to size the entire neck.
    As for wasting $ on neck sizer dies. The instuctions that come with RCBS 2 die sets, explain how to set up the FL sizer to just NS. So I guess you did.
  9. reynolds357

    reynolds357 Former Guest

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    Why does RCBS sell a neck sizer?
    If you do not size the full neck and bump the shoulder, you eventually get a sticky cartridge that does not chamber properly. Proper neck sizing makes a huge difference in accuracy. When you neck size by backing off a full length sizer, you are creating a load that is less accurate than a full sized case and much less dependable than a full length sized or properly neck sized case.
    Last edited: Nov 14, 2011
  10. woolleyworm

    woolleyworm Active Member

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    I do prefer to have both dies; this way I don't have to mess with the adjustments when I do have to FL resize. It is very possible to use a FL die to neck size and end up with great results. It's more of a matter of convenience for me. If I were shooting competition, I'd use bushing type neck sizing dies.
  11. JLA

    JLA Well-Known Member

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    In precisely cut match grade chambers yes.. But in those chambers you also need to neck turn to a specific dia, Keep the brass trimmed to a specific length, and seat the bullet a very specific point in the throat/lands of the rifle or it wont shoot well.

    In an off the shelf rifle costing well under a grand, intended for average folks, those competition grade necksizers are moot. And backing off the FL die to necksize works well for tightening up headspace and making the rifle average better groups.
  12. reynolds357

    reynolds357 Former Guest

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    I have a $300 Savage .270 win with an ultra light barrel that I load for the way you described above. Makes the difference between 1.5 MOA on factory loads and .38 MOA on handloads. (cold barrel groups of course) It is amazing how much difference turning the necks to a consistent diameter makes. I have found over the years that many of these rifles with very UN-match grade chambers love a perfectly neck sized piece of brass.
    For a true match grade rifle, it does not matter if you neck or full length size. Why? You have a set of dies made that are identical to your chamber and in actuality you are doing nothing but neck sizing with the custom made full length sizer.
    Last edited: Nov 14, 2011
  13. JLA

    JLA Well-Known Member

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    Youd be an exception to the rule and proof the factory can occasionally turn out a real gem in a production rifle.

    99% of factory production guns have too much runout at the barrel/reciever junction to ensure SUB MOA. Most of them will approach MOA with tedious handloading.

    When i first started building rifles I bought a Savage 11, with the then brand spankin new accustock. It wore a pencil thin 22" sporter barrel in .308 but would put 5 inside 2 inches at 250 yds all day. I pulled it apart and used the action to build a LR hunter. When I chased the threads with a mandrel tap from Pacific tool and guage the tap went in and didnt cut hardly anything off the threads, they got it right at the factory.. Then I refaced the reciever ring off the same mandrel and it too cut an even ring on the very first pass, I ordered a new barrel nut from NSS so I knew it was already trued. I screwed the new CBI barrel onto a manson go guage and set the jamnut with about 65 ft. lbs. of torque, headspace is less than .002" Itll shoot high .5s at 200 now. And with minimal action truing.. Only thing special im doin to the brass is weight sorting and deburring flashholes, then necksize only with a LEE collet necksizer. Shooting 175 SMKs over Alliant 2000MR lit with a CCI250.
  14. myfriendis410

    myfriendis410 Member

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    Another point about neck sizing using f/l dies; 1/2 turn away from f/l sizing is all you need to neck size and that amounts to .035" of neck not getting sized.

    It's also my experience, in a production rifle, that turning the neck has more value in small caliber cartridges like the .22-250 or .243. The ratio of bore diameter to neck wall thickness is higher in the small stuff and can have some effect on bullet tension when chambered.
  15. reynolds357

    reynolds357 Former Guest

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    Savage usually does get it right at the factory. Their barrels quite often need fire lapping, but other than that they are pretty much spot on with their assembly. That ugly little nut has a lot to do with that.
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