New brass short

Discussion in 'Reloading' started by MOOSE39465, Apr 17, 2012.

  1. MOOSE39465

    MOOSE39465 Well-Known Member

    Messages:
    130
    Joined:
    Nov 11, 2010
    Went to the store and picked up some 300 win mag Winchester brass. Made it home and started to prep my cases. Over have on them read under 2.610 which is minimum standard for SAAMI on 300 win mag brass. I can trim the brass to 2.608 and all of my brass will work. Am I messing up or is this common practice because I know Winchester brass seems to always run a little shorter then most?
     
  2. reelamin

    reelamin Well-Known Member

    Messages:
    123
    Joined:
    Feb 13, 2012

    Not sure but I think your saying to be able to trim every single case to the same lengh you would have to go to 2.608? If that is correct, and you absolutely have to have them all exactly the same trim them. .002 is a non-factor for brass OAL for 99% of shooting...but that is just me.
     

  3. MOOSE39465

    MOOSE39465 Well-Known Member

    Messages:
    130
    Joined:
    Nov 11, 2010
    The brass that I purchased is very inconsistent as far as length. I can measure one piece and it will be 2.615 and the other would be 2.608. I would like to trim them as close as possible but the majority are under 2.610 which is under the SAAMI specs for a 300 win mag. If it's not a big deal I would like to trim them to 2.608 so they are all the same length. Most of the time I will trim my new brass to what the book says and not trim them until they are getting close to maximum SAAMI specs.
     
  4. BK6x47L

    BK6x47L Member

    Messages:
    18
    Joined:
    Dec 28, 2009
    If they are all under max, one option is to shoot them, then size and trim. Once they are fireformed, you will be able to keep them at a consistent length.

    If you trim first, I think they will vary by a few thousandths after the first firing.

    If this is a hunting rifle, case length is probably moot. I haven't seen that varying case length affects hunting accuracy. If shooting F-class or other competition or your rifle shoots 1/4 min or less, then it may.

    I, too, used to get more hung up on case length. Your chamber is probably much longer than Saami, anyway.

    I now have chamber gauges to measure the length of MY chamber. then I trim .010 less than MY max length, which in some cases is still longer than SAAMI.
     
  5. MOOSE39465

    MOOSE39465 Well-Known Member

    Messages:
    130
    Joined:
    Nov 11, 2010
    Thanks for the info guys. I loaded up 40 last night for barrel break in and load development. I am trying to load for maximum accuracy so every little bit helps. The rifle is a custom built on a Sendero action and hopefully will be a shooter. if my scope ever comes in I will post some pics
     
  6. Gene

    Gene Well-Known Member

    Messages:
    1,326
    Joined:
    Jan 23, 2007
    I always trim virgin brass to .005" less than SAMMI. After first firing, try to keep them 5-10 thou under. Uniform length is more important than how much under. Some of my brass is even .020" under SAMMI. But the further back you trim, the better your chance of creating a carbon ring at the chamber mouth.