280 to 280 AI ???

Discussion in 'Gunsmithing' started by Idaho_Elk_Huntr, Feb 24, 2010.

  1. Idaho_Elk_Huntr

    Idaho_Elk_Huntr Well-Known Member

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    Dec 24, 2005
    Does the barrel have to be set back to rechamber 280 to 280AI??

    Thanks!!
     
  2. tackdriver10

    tackdriver10 Well-Known Member

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    136
    Joined:
    Nov 17, 2009
    Generally speaking, Yes.. My understanding is you want your Ackley Chamber to be .002 shorter on headspace than the parent case that it is derived from. Reason being, you will get good, tight fitting cases after you fire-form. Also, if you dont have a tight, crush fit on the original brass, and it jumps forward during fire-forming, you will like start having a few unexplained missfires...

    But, if you plan on buying factory .280 Ackley brass, and not fire-forming, then it wont be nescessary.

    .002 is no big deal for a good smith, unless you have engraving or a muzzle brake to keep in time. Then he may want to set it back one complete revolution of the thread shank and go from there...