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Thread: New brass vs old brass - with the same load

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    Member Rod in Wasilla's Avatar
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    Question New brass vs old brass - with the same load

    Will performance (velocity, POI, accuracy, etc...) change if load testing is done with new brass, and then that data is used to reload that same brass (now once-fired)?

    And if so, will there just need to be a little tweaking, or will the load load testing have to basically start over?

    Or, conversely, if there is a load that is known to work well in used brass, can that load be used in the first firing of new brass of the same headstamp?
    Quote Originally Posted by northwestalska
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    Default Talkin RIFLE here,

    I've always treated rounds with new brass, the same as those with used brass, assuming there would be no appreciable difference.

    On the other hand, I make sure my rifle is sighted-in for the same batch of loads I'm gonna hunt with.

    It's an interesting question, though.

    If there is a signicant difference in case capacity in an unfired case, versus a fired case, there could be some difference. Again, I'm suggesting, it's a very minor thing.

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    Member Rod in Wasilla's Avatar
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    Thanks Smitty. I figured as much. Just thought I'd ask.
    Quote Originally Posted by northwestalska
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    The difference , if any, should be very minor. The case will be expanded to full chamber size well before maximum pressure has occured. So, by the time full pressure has happened, both new or used cases should be the same provided they are of the same lot of cases. Or even if they weigh the same and are of the same length. Sometimes you can't get quite as much powder in a new case as one that has been fire formed and only neck sized. Especially if you have a chamber on the large size. You probably won't be able to tell the difference.

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    Quote Originally Posted by Rod in Wasilla View Post
    Will performance (velocity, POI, accuracy, etc...) change if load testing is done with new brass, and then that data is used to reload that same brass (now once-fired)? And if so, will there just need to be a little tweaking, or will the load load testing have to basically start over?
    When you change something (anything) in your reloading recipe I think the rule of thumb is to expect "change" in its performance. Is the change going to be significant? Well that depends on the specs of your chamber and the dies that you use, among other things. I neck size almost everything and there is some reduction in velocity in my rifles when using fire-formed brass in place of virgin hulls if all else remains equal.

    Quote Originally Posted by Rod in Wasilla View Post
    Or, conversely, if there is a load that is known to work well in used brass, can that load be used in the first firing of new brass of the same headstamp?
    I expect variation when using different lot numbers of a manufacturerís component whether that component is powder, brass case or primer. If your load is a maximum load then prudence would deem a reduction in your powder charge a wise move until you establish that the max load is not an overload with the change in components.

    All of this to say that once you have established a preferred load for a particular rifle, that load may vary with the use of replacement lots of components. IME the variation will be a difference in degree not in kind. For conversation, I have a 270 Winchester that I load 140 NBTs at Ī 2960 fps with a near max load of RL 22. This has proven to be an extremely accurate load in my rifle, but the precise powder charge varies depending upon the particular lot of powder, brass or primers I am using. For instance when I start with a new lot of brass (all other components lot #s remain the same) I step down from the maximum load a few grains, chronograph my results and work my way up. I am aiming for a particular velocity threshold (without pressure signs) and when I get there I know it's good.
    Esse quam videri

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    Good info on here. Keep in mind that virgin brass is undersized so it will fit in all chambers. It will grow to fit your chamber and that may results in a little more case capacity in some production rifles.

    If your selection of components benefits from a higher charge then neck sizing will benefit you. Neck sizing also allows the shoulder and case body to completely fill your chamber. That will provided a solid foundation for your case to launch your bullet with better bore alignment and less delay during combustion, splitting hairs here.

    If you full length resize you end up about where you started prior to fire forming depending on the specs of your production chamber. I like to set the shoulder back .002 on all my rounds. It gives good accuracy for me and assures a positive fitment and smooth bolt closure.

    With my 204 I just whack varmints and let the kids have fun at the range. I use 200 cases 50 each from 4 different manufactures. All cases are sized and prepped to the same exterior measurements. The only difference is web and wall thickness and that affects internal capacity. These loads are within 40fps of each other, 3800-3840fps. I imagine this would be about the same as virgin brass versus fire formed in terms of velocity.

    Evidence shows fire forming and neck sizing can result in more accuracy.

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    When I settle on a load, it's usuallly been with fired brass.

    One thing I've noticed, is when I FL size New UnFired brass, is that the die usually doesn't hardly touch the body of the case. That's why I think there, Could Be, some difference in capacities, depending on the particulars.

    IME, I can't say I've ever noticed any difference in the shooting or sight-in.

    Howsomever, I can appreciate what 1 Cor. said, safety wise, regarding a MAX load, etc.

    Our load could be closer to MAX, than we realize. I might oughta pay closer attention, to this.

    Smitty of the North
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    Has it ever occurred to you, that Nothing ever occurs to God? Adrien Rodgers.
    You can't out-give God.

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    Member Rod in Wasilla's Avatar
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    Definitely good info. I appreciate the feedback, guys.
    Quote Originally Posted by northwestalska
    ... you canít tell stories about the adventures you wished you had done!

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