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Proof formula

Discussion in 'Blackpowder' started by jimrbto, Aug 21, 2008.

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  1. jimrbto

    jimrbto Member

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    While going through my safe today I came across the original proof of proof card that came with an 1851 Navy Colt I bought in Germany back in '59, try as I might I cannot find this formula anywhere except for a concrete peneteration meter. As stated on the card the gun was proofed at "620 Kgr/cmq". I have seen a lot of formulas in my day but never this one. The "cmq" is the part I have never seen before.
    Any ideas?
     
  2. Drgong

    Drgong Member

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    sure it not Cm2?

    In that case it was proofed to 8,800 PSI or so...
     
  3. Omnivore

    Omnivore Member

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    Pressure per unit area. Square centimeters would definitely make sense, as the units would be consistent. Sure it's not "cmsq"?
     
  4. jimrbto

    jimrbto Member

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    I should have said that this "shoe tag" is all in Italian. The front is preprinted with spaces to write in the serial no. etc. If needed I can type everything that is on the card and on the back but the part I am interested in is on the front and states:
    Pressione di Prova Superata
    620 Kgr. / cmq
    I am assuming that the above is the proof data.
    Perhaps back then the Italians had a way or stating a formula we aren't familiar with?
    Thanks .........Jim
     
  5. mykeal

    mykeal Member

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    Centimeters squared in Italian is "centimetro quadrado", abbreviated as cmq.
     
  6. bigbadgun

    bigbadgun Member

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    Pressione di Prova Superata=Pressure to Pass Test
    Best I can offer
     
  7. Drgong

    Drgong Member

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    Your gun was proofed to around 8,800 PSI, as it is the Kgr/cmq is multipied at 14.xx (I think it is 14.22, but I can be wrong) to get PSI, which gives you the PSI of around 8,800 PSI.
     
  8. jimrbto

    jimrbto Member

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    Thanks everyone, I assumed that the "cmq" probably meant sq. cm.
    however you all know what ass-u-me means. When I googled that formula and came up with four hits all pertaining to concrete penetration it kind of threw me.
    That means that my barrel was proofed to 8818 lbs/sq in. I wonder what the proof standards are today for bp barrels of various types.
    Thanks again
    Jim
     
  9. Jim K

    Jim K Member

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    That is, of course, the black powder proof, as the "PN" (polvere nera) proof mark shows. Smokeless powder proof pressures for modern guns would be much higher.

    I am sure the proof loads are the same today, and would be the same in every country that has a proof law. Once set, those proof rules rarely if ever change unless there is a new type of powder (as in the change from black to smokeless around 1900).

    Jim
     
  10. Loomis

    Loomis member

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    Pressione di Prova Superata

    Proven beyond pressure
    Prooven to exceed
    minimum proofed pressure


    you get the idea.
     
  11. mtngunr

    mtngunr Member

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    And it means the cylinder, not barrel, held proof....getting over 8000psi in a front-stuffer cylinder was plenty....
     
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