Will virgin brass cause more pressure?

Discussion in 'Reloading' started by KQguy, Apr 28, 2010.

  1. KQguy

    KQguy Well-Known Member

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    I have a load that I use for my 7mmWSM,that I developed a year ago,I have only shot it using fired brass.My load is at max charge,according to published data,although I have no pressure signs.If I load up some of the same powder charge,but using virgin brass,will anything change as far as pressure goes?
     
  2. Tikkamike

    Tikkamike Well-Known Member

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    Technically yes it should but it will be such an insignificant amount you wont see it. If you worked up your load to "book" max and stopped just because that is where the book stopped chances are you are quite a ways under your real max anyway. So have no fear of new brass.
     

  3. royinidaho

    royinidaho Writers Guild

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    Well stated!
     
  4. bigngreen

    bigngreen Well-Known Member

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    I had a lot of head space on my 270 WSM and with new brass I had to fire form before max load or it would lock the bolt, the pressure was the same but the case couldn't get blown out to the side walls and get any traction before the case was shooting back and slamming into the bolt face.
     
    Last edited: Apr 28, 2010
  5. boomtube

    boomtube Well-Known Member

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    "Will virgin brass cause more pressure? "

    No. By the time the chamber pressure reaches about 30-35k psi it all fits the chamber quite well.
     
  6. KQguy

    KQguy Well-Known Member

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    OK,thanks guy's.I just wanted to make sure,better safe than sorry.
     
  7. Bravo 4

    Bravo 4 Well-Known Member

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    While I would tend to agree with using virgin brass and max loads I don't agree with the statement above. My Savage 7mag will show pressure signs with 3grs powder less then "The Book" max with same brass, primer, and OAL. The one size fits all doesn't apply to reloading.
     
  8. Kevin Thomas

    Kevin Thomas Well-Known Member

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    Guys, the "book max" actually IS a maximum load, albeit in the gun and component combination that the makers of that particular manual used to develop that data. You're dealing with something different, even if you're using exactly the "same" components listed in the manual. Different lot of powder, primers, brass, not to mention an entirely different rifle. You may very well be able to exceed these loads without a problem, but you can just as easily find situations where you can't reach those top loads shown without being in the red zone already. There IS NO "safety fudge factor" built into any manual that I'm aware of, and that accumulation of tolerance issue (regarding the different lots of components) can stack in either direction. Two eyes and ten fingers, and we don't get issued any more after those are gone, if you get my drift.

    Kevin Thomas
    Lapua USA
     
  9. Tikkamike

    Tikkamike Well-Known Member

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    Bravo 4 and Kevin Thomas,

    I agree with you maybe I just did not articulate properly. I am not saying one load fits all guns that is very much not true. What I was trying to say is if he was working up his load and had no pressure and stopped only because he had reached the max that was listed in the book then he probably had more room to go. "Book max" is max as far as pressure goes. but like kevin said some guns and lots of powder and primers give different results it is a matter of reaching that max pressure listed in your manual and having the experience and know how to recognize the signs that you are exceeding a safe pressure. But I think everyone here agrees that the new brass will not cause higher pressure. and if it does it is minute because the brass expands easily to fit the chamber anyway.
     
  10. Kevin Thomas

    Kevin Thomas Well-Known Member

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    Hey Mike,

    No, we're on board here. The new brass alone shouldn't cause a problem, assuming it really is a match for the original fire-formed stuff in question. I just get a bit touchy about the "built in safety factor" assumption that many folks seem to harbor, and tend to pounce on such discussions. Like I said, I've dealt with a lot of manuals over the years, and written a few myself. The best way to look at them is as a report. In other words, "we tried this component combination, and these are the results we saw." Personally, I'd like to see that followed with a cautionary "your mileage may vary" warning, but the powers that be (in my old job anyway) just have no sense of humor!:D

    Kevin Thomas
    Lapua USA
     
  11. boomtube

    boomtube Well-Known Member

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    "...maybe I just did not articulate properly. I am not saying one load fits all guns that is very much not true. What I was trying to say is if he was working up his load and had no pressure and stopped only because he had reached the max that was listed in the book then he probably had more room to go."

    Mike, you spoke clearly the first time. And correctly.