Neck size only

Discussion in 'Ammunition & Reloading' started by FA9, Mar 31, 2016.

  1. FA9

    Hillsburrito, ORgun
    Well-Known Member

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    Thinking of buying the lee collet die, on lee's site it says "Not recommended for autoloaders".

    I was thinking of neck sizing only for my ar10 brass and possibly ar15 also, but I just read that its not recommended. Why is that?
  2. PaulB47

    Well-Known Member

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    I never heard that before.

    The collet die does leave slightly raised ridges longitudinally along the neck, maybe they figure these can be tall enough to make chambering iffy, where it wouldn't be in a bolt gun? All I can guess. Maybe it's just "lawsuit avoidance tactics".

    Oh, another possibility is that maybe you want to always full length size cases for semi-autos anyway? Otherwise how can you ensure a couple thousandths of headspace?

    I tend to avoid reloading for semi-autos. A lot more stuff you have to worry about.
    Dyjital and FA9 like this.
  3. Scott F

    Scott F
    Oregon City, OR
    Active Member

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    Works great in a bolt gun but often will not fully chamber in a semi auto. Full length is the way to go for ARs.

    I neck size for most of my rifles but would not use the Lee colletdie. I perfur a bushing neck die.
    FA9 likes this.
  4. Otter

    Well-Known Member

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    Fairly tight fitting brass in a bolt gun is good but in an auto it might not cycle properly.

    I quit neck sizing only when I had a couple bolt rifles where the brass would stick, even before firing. Full length sizing and bumping the shoulder back about .002 in a bolt action is all I will do anymore. Accuracy is the same or better.

    In an AR, it is suggested .004 to .005 bump to the shoulder. Some ARs even need a small base die to squeeze the base of the case small enough to feed and chamber.
    FA9 likes this.
  5. Dyjital

    Albany, Ore
    Flavorite Member Bronze Supporter

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    No. Full length size all auto loaders and pump style firearms.

    Imagine this....

    When a case is fired and after the brass recovers and shrinks a little.. Let's say the shrinkage is .003" at the base/body. Let's even say one piece of brass doesn't shrink at all and is exactly fire formed to your chamber....

    Now you want to quickly feed that into the chamber again and again and not expect it to do it smoothly...

    All you need is .005" or less especially headspace variance from your chamber to brass to cause a failure to enter full battery.

    I had .003" of excessive non bumped headspace in my AR-15 brass and that required me to undo 200 rounds and bump the shoulder back. Neck only does not bump shoulder. No shoulder setback = no full battery....
    eightyeight mag likes this.
  6. AMProducts

    Desert Southwest
    Jerk, Ammo Manufacturer Silver Supporter

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    Go buy yourself a nice small base die set, you need to completely size the brass, not just make the mouth hold a new bullet, even then that lee collet sizer is junk. The lee FCD is awesome, but it's the only lee product I've willingly spent money on in 10 years.

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