280 AI alert

Discussion in 'Gunsmithing' started by J E Custom, May 30, 2011.

  1. J E Custom

    J E Custom Well-Known Member

    Jul 29, 2004
    I am in the process of building two matching 280 AIs and after reading everything that
    I could find I though I knew the way I wanted to go.

    The desire was to simply place a 280 Rem in the 280 AI Chamber and fire form it.

    And with all the rhetoric about Nosler changing the SAAMI dimensions I decided to
    go with caution and use both head space gauges because I kept coming up with a
    difference in the two as far as head space.

    Wanting the fireforming process to also be accurate with the 280 Rem for hunting, I checked
    head space often while chambering with both the 280 and the 280 AI go gauges and kept
    coming up with the same difference.

    Once the head space reached .000 with the AI gauge I checked it with the 280 Rem gauge
    and had .0065 + , then I tried a loaded round and it was .006.(The bolt would not close on
    the 280 Rem gauge).

    So I chambered .006 deeper to allow the 280 Rem to head space, then I rechecked the
    head space with the 280 AI gauge and had .006 thousandths(Two much).

    This means that it would be possible to fire Nosler 280 AI in it but not advisable because
    of the near Maximum head space.

    All of the other AIs work great and are very accurate while fire forming, And why(I think I
    know) they would make it this way Instead of just loading ammo with the AI head stamp
    is beyond me. There is only one choice of ammo if you want the AI on the case head, but
    there are dozens of choices for the 280 Rem.

    My point of this post is to warn people about firing Nosler 280 AI in there 280 Ackley or
    trying to get 280 Rem in one of the "New" AI chambers. (The only way you can find out
    what you have is to have two head space gauges).

    I buy lots of Nosler products but this will not be one of them.

    Just my 2 cents.

    Last edited: May 31, 2011
  2. shortgrass

    shortgrass Well-Known Member

    Mar 31, 2010
    I don't know how Hornaday might change head space dimentions. When chambering an Ackley the "go" gage for the parent cartridge, in this case the .280 Remington, becomes the "no-go" for the Ackley chamber. Ackley chambers are shorter than their 'parent' cartridges. That way the case, when fire forming your .280 Rem. brass to .280 AI, is fully suported. Did I misunderstand your post? The bolt should close 'snuggly' on a .280 Rem. round when placed into a .280AI chamber.
  3. J E Custom

    J E Custom Well-Known Member

    Jul 29, 2004
    That is correct, and that is the way I chambered it but if I had used the new 280 AI head space
    go gauge the 280 Rem would not chamber.

    I talked to several reamer makers and they said that they have to cut there reamers to the "NEW"
    dimension because it is the SAMMI spec now that Nosler has submitted it as the standard and
    SAMMI has adopted it as submitted. You can still have a wildcat reamer cut but it will not be the
    standard any more.(The old 280 AI reamers were cut like all the rest to use the parent case
    head space gauge).

    When I head spaced with the 280 AI go gauge the 260 Rem head space go gauge was .0065 to long
    and the bolt would not close on the gauge, and on a factory round head space was .006 and still
    would not close even with lots of pressure.

    All of the other AIs use the neck to shoulder junction to head space the standard round and shoot
    extremely good while fire forming.

    I hear what you are saying about the go no go gauges but I can't make myself cut a chamber with
    .006 Thousandths head space. originally I had thought about splitting the difference but decided
    not to take a chance on the accuracy of the rifle and go with .0005 head space using the 280 Rem
    head space gauge so there would be a little compression of the case on the bolt when closing.

    So this way the chamber will be .006 longer than the NEW SAMMI 280 AI CHAMBER in order to
    use the 280 Rem ammo.

    I hope this explains the problem better.

    Again maybe I'm to fussy about head space.

    Last edited: May 31, 2011
  4. KRP

    KRP Well-Known Member

    Dec 25, 2007
    I thought it was Nosler that did this? They are the only ones I know that make factory 280AI ammo/brass.

    FEENIX Well-Known Member

    Dec 20, 2008
  6. J E Custom

    J E Custom Well-Known Member

    Jul 29, 2004
    Sorry !!!!!
    I did it again.Thanks for catching it.

    It was Nosler.

    Last edited: May 31, 2011