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Thread: 6mm PPC

  1. #16
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    Quote Originally Posted by David Halblom View Post
    what you are describing is you assume a USA chamber. The 6 PPC USA chamber is considerably bigger than virtually all the various benchrest 6PPC chambers. That is so the benchrest cartridges we use in competition cannot be shot in a factory rifle and the factory USA rounds will NOT fit in our benchrest rifles.. That is the one MAJOR issue that must be determined by the original poster, what chamber does he have?
    David,

    The Norma Brass may say 6MM PPC USA on the headstamp, but like I said I have (now two) 6 PPC's and they are both tight neck .262's. One of the 6 PPC's use to belong to Jack Neary. You may want to see this video by Lou Murdica, who recommended the Norma Brass: http://www.youtube.com/watch?v=QAFleA_mQv8

    I have found the brass to work excellent as have many of the fellow benchrest guys I shoot with at Camillus.

    Ed
    Last edited by ehkempf; 07-20-2013 at 08:38 PM.

  2. #17
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    Quote Originally Posted by David Halblom View Post
    what you are describing is you assume a USA chamber. The 6 PPC USA chamber is considerably bigger than virtually all the various benchrest 6PPC chambers. That is so the benchrest cartridges we use in competition cannot be shot in a factory rifle
    Uh, David, that doesn't make sense. A slightly smaller round will fit in a slightly larger chamber & can usually be fired.

    That said, the older Norma 6PPC brass measured around .436 or .437 at the head; Lapua .220 Russian is closer to .4385. The sizing die will take care f any other issues, except chamber length. Usual with "Benchrest" 6PPC reamers is about 1.520. That, I suppose, so the .220 case would fit to fireform. The cases shortened up to a bit less than 1.51 when fireformed -- 1.500 not uncommon.

    I have no idea what chamber depth the 6PPC USA reamers cut, maybe less. But I've used the USA-stamped Norma cases in my small-chamber PPC. With the old AA 2017-BR powder (circa 1996), they shot very well with the lower pressures that powder liked.

    FWIW

  3. #18
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    C.I.P. 6 P.P.C.- U.S.A. page 69

    This is the chamber that Norma uses.
    email from Ake Nilsson Research & Development Norma

    http://www.poliisi.fi/intermin/image...le/TABIcal.pdf

    Glenn
    Last edited by Stonewall; 07-21-2013 at 02:51 PM.

  4. #19
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    Quote Originally Posted by Badmouser View Post
    Just bought a Remington 40x with a Hart Barrel, chambered in 6mm PPC. Got a box of 220 Laupa to fire form. If I load the cartridge normally what bullet would I use since 6mm will not yet fit? Would a smaller bullet harm the barrel?

    It's probably a stupid question, but just starting out.
    Thanks
    Please, please, please do not make assumptions about the neck in that chamber. You could get into a very dangerous situation really quickly. There are both neck diameter and neck length questions.

    For example, even if you get the diameter right but push a benchrest pressure round with a generous length neck into a short necked chamber, you will get an over pressure situation.

    Better safe than sorry: Get a gunsmith to make a chamber cast of the chamber.

  5. #20
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    Quote Originally Posted by SGJennings View Post
    Please, please, please do not make assumptions about the neck in that chamber. You could get into a very dangerous situation really quickly. There are both neck diameter and neck length questions.

    For example, even if you get the diameter right but push a benchrest pressure round with a generous length neck into a short necked chamber, you will get an over pressure situation.

    Better safe than sorry: Get a gunsmith to make a chamber cast of the chamber.

    This is the best advice on determining chamber dimensions. You can do it yourself. I use a product called "Cerrosafe". to make a chamber cast. Brownells carry it. What you end up with is an exact copy of your Chamber.

    Takes the guess out of trim length and neck diameter.



    Glenn

  6. #21
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    Sorry Charles,

    Quote Originally Posted by Charles E View Post
    Uh, David, that doesn't make sense. A slightly smaller round will fit in a slightly larger chamber & can usually be fired.

    That said, the older Norma 6PPC brass measured around .436 or .437 at the head; Lapua .220 Russian is closer to .4385. The sizing die will take care f any other issues, except chamber length. Usual with "Benchrest" 6PPC reamers is about 1.520. That, I suppose, so the .220 case would fit to fireform. The cases shortened up to a bit less than 1.51 when fireformed -- 1.500 not uncommon.

    I have no idea what chamber depth the 6PPC USA reamers cut, maybe less. But I've used the USA-stamped Norma cases in my small-chamber PPC. With the old AA 2017-BR powder (circa 1996), they shot very well with the lower pressures that powder liked.

    FWIW
    I got the dimension A##-backwards. But the principle is the same. A USA chamber and a typical br chamber are not one and the same. And we/he has no idea what chamber is in the rifle he is asking about. He needs to proceed w/ caution and make NO ass-umptions.

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