PRESSURE SIGNS

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by skeeter, Sep 7, 2004.

  1. skeeter

    skeeter Well-Known Member

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    OK fellows.
    If i have a round shiney flat spot on the end of my case[end witch primer is on]does this mean my presure is to high or i'am at high presure signs and could keep load at this powder charge.Primers look to me a little flaten????I my just back down 1/2 of a grain.@ 81.0 go to 80.5 iam getting 3860 fps.I dont know how much this is going to slow me down.
    Thanks SKEETER
     
  2. sniper2

    sniper2 Well-Known Member

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    This is one of the signs I look for, also flattened primers and hard extraction.You might get by with this load but don't try it in a few degrees warmer weather,I'd go down with the load if it were me just to be sure.I used to really push the envelope but have gotten smarter!
     

  3. Guest

    Guest Guest

    ejector marks on the case head are a good indicator that you getting into high pressure and the load should be backed off , normaly the ejector marks will show up a littlebit before the flattened primmers unless your using soft primers like Federal

    going by sticky case extraction is a dangerous way to note pressure. I had a hot load worked up for my Holland built 308 , it has a tight match chamber , the load was flattening primers and had some sticky bolt lift in hot weather , a buddy decided to try them out of his gun (unknown to me)which was a Rem 700 VS , the second shot galled his bolt shut , he said he should have know when he had to beat the bolt open on the first round.
    In short , as soon as you get signs of pressure back off , the few extra FPS you gain isin't worth getting hurt and your gun will probably shoot better anyway
     
  4. Guest

    Guest Guest

    what caliber , load and gun are you shooting skeeter ??
     
  5. Aussie

    Aussie Well-Known Member

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    Skeeter ,
    If you're getting pressure signs in a case that holds over 80 gns of powder then you need to back off by much more than half a grain to have a significant effect . That's only about 0.6% in a case that size .
    If you want a load where cases will last for a while then back off until you can rechamber and close the bolt easily on fired cases .
    An extra 100fps is hardly noticeable in terms of flattening your trajectory and game can't tell the difference .
     
  6. skeeter

    skeeter Well-Known Member

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    jdjones
    Its were i went up a 1/2 a grain on .257 stw and set back the bullet .050. For soom reson i can tell if the primer is flatting or not.But this is the only sign i see.The bolt problem we solved.
    SKEETER
     
  7. JustC

    JustC Well-Known Member

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    How strong is the ejector spring? If you don't have sticky bolt lift I would say yoy are still on the ragged edge of safety. ANY pressure sign,..even without the others is time to take notice. Very Bright ejector marks are a sure sign of too much powder,...back it off.

    Does it continue to group better as you reach this Point? if not,.back off to the last,..most accurate load. You are probably way too far at this point.
     
  8. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Skeeter, to give you an idea on how much ejector mark is acceptible(shiny spot on case head), I recently tested a box of Rem 7mm RUM and 300 RUM factory ammo.

    Upon firing in Rem factory 700 rifles, each case for both calibers showed just a faint extractor mark. You could see it but it was not obvious and shiny.

    This is what you should be going for.

    BUT!!!

    If your cases are tight when you chamber them and if you have a slight burr on the lip around the plunger ejector in the bolt face, this will give a false rub on the case as well when you unload the case from the chamber.

    To test pressure you should really be using virgin or once fired brass. Old brass will not tell you accurately what is going on.

    Good Shooting!!

    Kirby Allen(50)