Should I Outside Neck Turn My Brass?

Written by Ballistic Technician Paul Box

ImageThis is a question we get just about every week. Should I neck turn my brass? Well, the answer can be yes….and no. Let’s look a little deeper into it.

Naturally, if we had our favorite gunsmith chamber a rifle with a “fitted” neck we’ll have to neck turn in order for it to fit our chamber. But what about a standard SAAMI spec chamber? This all depends on the quality of your brass. Namely your case neck thickness variation. What I do is take a ball Mic and check the case neck thickness at “8:00 o’clock, 12:00 and 4:00 o’clock points. If my thickness variation is .001” or less, I wouldn’t outside neck turn. Unless we’re shooting 1,000 yd. benchrest I don’t think you’ll see any difference in accuracy if this thickness difference is any smaller than that.

Our main goal in outside neck turning is to give our seating die it’s best chance to seat a bullet with good concentricity with as little of run out as possible. This puts our bullet in better alignment with the center of the case body and in a squared and trued action, more perfect alignment with the bore.

Brass that has a neck thickness difference that’s more than .001″can be turned down to this spec and will shoot fine. They’ll also have the advantage of not being too thin, which will give early case neck splits and short case life.

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4 Responses to Should I Outside Neck Turn My Brass?

  1. David Duncan says:

    I turn enough to even up the neck on the cases (about 50 to 60 percent)
    for even bullet neck tension as it could only add to accuracy in my opinion.


  2. Brian Mathews says:

    I’m curious if there is a difference on inside neck turning or outside? I have a L.E. Wilson case trimmer and just purchased the neck turning cutter which trims the inside of the neck. I guess I need to get a ball Mic.


    • Yes, there is a difference between inside and outside neck turning and yes, to proceed you are going to need a ball mic. To discuss this further with one of our ballistic technicians, please call us toll free at 1-800-223-8799. We will be happy to help.


  3. Stan Wollard says:

    Good note. I have never neck turned my cases and get very good accuracy. Having red your note will check and see if turning improves. Not a Bench Rest shooter but strive for accuracy and good groups.


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