Fireforming Pressures

Discussion in 'Reloading' started by J300UM, Jul 1, 2008.

  1. J300UM

    J300UM Well-Known Member

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    This may be a stupid question, but does anyone know how much pressure it would take to fireform a 300rum case to an improved version. I have a chart from quickload showing pressures at given charge weights. I was hoping to save myself a little time by not having to go through a load developement process just to find an adecuate forming load. Thanks!!!
     
  2. royinidaho

    royinidaho Writers Guild

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    In accordance with instruction from the maker of my 270 Allen Mag which based on the 300 RUM case and improved w/a steeper shoulder I do the following.

    Resize leaving a 0.1" or so shoulder so the case doesn''t jump away from the bolt face.

    A non magnum primer

    20 grains of Unique

    Fill with corn meal. Shake down and refill.

    Top off with one square of TP to seal 'er up.

    Fire away.

    Don't go too fast as the barrel heats rapidly.


    Saves wear and tear on the barrel but kind of warrants a trip to IHOP aftwards.;)

    However, there has been some difference in performance in some precision rifles between the first full power shot and subsequent shots with the brass. This is a very slight but noticeable different and only in some rifles and most noticeable at far distances.

    I'm about to do a hundred 7mm RUM cases with this method as soon as those suckers get here.
     

  3. big wally

    big wally Member

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    When fireforming my 17A/H from 22Hornet brass i use the identical load as my hunting ammo but i am not loading up to max i load for accuracy and my fireform loads shoot to same P O I as my hunting ammo.
    I tried a lower charge but the shoulders did not seem as sharp as needed.
    Wally
     
  4. big wally

    big wally Member

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    When fireforming my 17A/H from 22Hornet brass i use the identical load as my hunting ammo but i am not loading up to max i load for accuracy and my fireform loads shoot to same P O I as my hunting ammo.
    I tried a lower charge but the shoulders did not seem as sharp as needed.
    Wally
     
  5. Sully2

    Sully2 Well-Known Member

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    Just chose a midrange load or a load slightly above midrange. You need enough pressure to blow the casing out to fill every nook and crannie and no more. More wont hurt anything...but just isnt needed.

    Some guys just load up a minimum hunting load and take it from there
     
  6. Outlaw6.0

    Outlaw6.0 Well-Known Member

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    My first Ackley improved cartridge was the.243AI, Sierra's tech line advised that I utilize a cheap bullet loaded long enough to jam into the lands when the bolt is closed (same function as Roy's ghost shoulder) with a load toward the max end of the spectrum for that bullet.

    that particular method had formed hundreds of .243AI & 6mmAI rounds for me to great effect.

    In a particluar 6.5-06AI that I load for, we use the cornmeal method described above (with a little less powder:D). The shoulders aren't perfect but close, the next firing established sharpness of the shoulders.


    t
     
  7. azsugarbear

    azsugarbear Well-Known Member

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    Just a word of caution when using the cornmeal method: if your barrel has a brake on it, be sure to remove it before fireforming your rounds. The fiber in TP or cotton, when used as a plug in the end of the brass to hold ther meal and gunpowder in, can get caught in the baffles or gills of the brake. It has enough force to crack or break the metal baffles. (Please don't ask how I came about this little gem of truth).
     
  8. boomtube

    boomtube Well-Known Member

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    A conventional load for the base cartridge will do the job fine, no fast powders or cornmeal, etc, is needed.
     
  9. kass

    kass Well-Known Member

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    Anneal your cases, charge cases to upper end of unimproved case/bullet combination, make sure that bullet is slightly into the rifling to insure case head location against bolt head and fire for effect. You should find that they shoot fine and accurate, you can then work up improved loads afterwards. Those FF loads can be used for breaking in, fun or any other use . I shot paper for a more than a few years and saw NO increase
    in groups when using FF loads.
     
    Last edited: Jan 18, 2013
  10. Outlaw6.0

    Outlaw6.0 Well-Known Member

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    One thing I want to make crystal clear in case it hasn't been discussed yet.

    DO NOT, seat a bullet on top of a case full of cornmeal. You will blow the rifle up in your face. Paper only on top of cornmeal.


    t
     
  11. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    Yep, if you want to scrub the heck out of your rifle after using the pistol powder and cornmeal method go right ahead, but NO BULLETS ON TOP of it.

    I actually prefer if I HAVE to use cornmeal(or farina) to charge the casings at the range and shoot into the air (when no one is there) and not bother with a paper plug.

    I prefer a false shoulder, cheap bullets, and a mid-range load from the former caliber.
     
  12. big wally

    big wally Member

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    I did see a photo of a brake that had been left on when fireforming with tissue paper as a wad.
    It was not a pretty sight.

    Wally
     
  13. big wally

    big wally Member

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    What is the use of fireing a charge of powder into the air or a wad of cornflower and paper either if you want to make a bang use a air filled paper bag.
    Use a proper loaded cartridge on paper or on game and have fun doing it.
    If nothing else the practice has got to help your grouping or game bashing.

    Wally
     
  14. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    ???

    The pistol powder with the cornmeal on top blows the casing out just fine. I don't like fireforming that way as it makes the rifle filthy and I'd rather shoot the dang thing anyway.