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Thread: Overall Lenght Gauge & Accuracy?

  1. #1

    Default Overall Lenght Gauge & Accuracy?

    I have a Stoney Point OAL gauge that I used for my 300rum. The manuals are saying to load these rounds with an OAL of 3.6 inches. With the gauge it says my OAL is 3.784. I am told to back my OAL by .030 and load my rounds for 3.754 inches. Thats .154" difference between manual SAAMI overall cart. length and the OAL gauge back off by .030. I hear the SAAMI is set more for safety and the fact that this length should work in all guns of that caliber.

    In a general sense of the term how much more accuracy is accomplished by loading rounds to the OAL dictated by a gauge and backed off by .020 or .030 compared to the SAAMI overall catridge length? Also is there anything in particular to be careful of when using an overall length gauge and it's measurements?

  2. #2
    Join Date
    Jan 2005

    Default Long Enough...


    Typical free bore for the RUM's and WSM's is .200". It will be hard to get a bullet within .030" of the lands and fit it in the magazine. There may or not be a significant difference in accuracy with cartridges of this type (big) by varying the seating depth. The WSM's will respond to it but usually not the Ultra's. I beleive the SAAMI length is what the magazines are made to. You might get 3.630" in the magazine, but that's about it. The best tip for accuracy in those calibers is not fully resizing the case, this gives much better bore alignment and that has more of an effect than seating depth. Also you want the neck to have a good grip on bullet, seat to the bottom of the neck. I would just neck size and seat to the neck length if that fits the magazine, if not, deeper.
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?

  3. #3


    Thanks Murphy, exactly what I was looking for.

  4. #4


    I have two 300rum's one rem one a win. they were each very tempermantal about col when shooting barnes xlc-xbt's a diffrence of a few thousandths and it went from great to horrible. both were very different lengths. I now use the tsx and it seems to not give a rip about col. I set the length for reliable feeding and they shoot good. if it was 5 years ago I would have never even thought that was an option.


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