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subsonic load for 308

Discussion in 'Ammunition & Reloading' started by giddyupgo55, Jun 11, 2009.

  1. giddyupgo55

    giddyupgo55 Vernonia Active Member

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    I'm looking for subsonic load data for the 308 with a 200 grain bullet. Can anyone one help? Thanks
     
  2. torpedoman

    torpedoman land of corrupt politicians Member

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    you have to lob a 22 subsonic at 75 yds and it is a 40 gr bullet it may not be a practical load. but you'll need a crony because it is going to vary a lot what is subsonic from one gun won't be with another, barrel length, barrel condition,and many other variables.
     
  3. giddyupgo55

    giddyupgo55 Vernonia Active Member

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    as you said I will be needing a crony to continue with this project. I'll keep at it and hope more info comes in as I move forward. Thanks
     
  4. SVT

    SVT N. Seattle Member

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    Go the accurate reloading forum http://forums.accuratereloading.com and lookup post by "seafire" and Blue Dot. You will find formula's he came up with for working up Reduced Velocity (but not low pressure) loads using Blue Dot. These loads will NOT cycle a Semi-Action. I just worked up some loads using a .308 reduced capacity case. I'll probably go out over the next couple of weeks and work up some loads using Lake City Cases.

    His formula was to fill a case until it overflowed...
    Then level it off even with the rim of the cartridge, and then weigh the amount of Blue Dot for a full case...
    20% of that figure is the recommended Minimum load...
    30% is a good starting point to work up loads..
    40% of that figure is a good point to proceed slower...
    This is where it gets important....
    50% of that figure should be in the neighborhood of Max, if the case is based on a 30/06 case....
    work up slowly and in small increments above 50% of max in magnum cases, 308 and 7 x 57 based cases...
    Max will be near 60% of full capacity in most cartridges depending upon bullet weight...( except 30/06 based cases.. IE.. 25/06, 270, 280, 30/06, 338/06, 35 Whelen)
    Mag cases.. like the 7mm Rem, 300 Win, etc... work up to the 50 % rule... WSM short mag cases are more forgiving.. Blue Dot seems to have an affinity for short and fat...
    Large Rifle primers are recommended, even in Magnum cases...
    Blue Dot is not position sensitive in rifle cases, even with only 20% of max as a charge...
    NO FILLER is recommended, as it will actually increase pressures....
    Do NOT consider Blue Dot for maximizing velocity potential of a rifle case..
    Consider it for accuracy and reduced velocity loads... at 40 to 50% you are not shooting reduced pressure loads.. just reduced velocity loads...
     
  5. toys

    toys PDX Member

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    this should be interesting
     
  6. torpedoman

    torpedoman land of corrupt politicians Member

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    one other thing, to maintain a consistent burn with a greatly reduced powder charge some type of wad may be needed to keep powder in place, and PLEASE check your bore after each shot.
     
  7. SVT

    SVT N. Seattle Member

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    No Wad or Filler for the blue dot. It can increase the pressure and it isn't position sensitive. Don't go below the 20% level.
     
  8. jib

    jib Central OR Active Member

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    I have used Blue Dot for .308 Win. with very good results for reduced loads, but these loads were not sub-sonic.
    I would try IMR's Trail Boss with cast bullets, Red Dot would be another powder to consider.
     
  9. Hotwheelz

    Hotwheelz Pierce County Member

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    IN my lyman 46th edition manual it has some load data for cast bullets in .308.
    Here is there recipe for a 178gr bullet this is the heaviest cast bullet they show.

    reddot 10.0gr 1352fps
    700x 8.0gr 1200fps
    green dot 11.0gr 1424fps
    PB 9.5gr 1240fps
    unique 10.0 1373fps


    These are the 5 slowest loads they show this may give you a starting point. Hope it helps
     
  10. SVT

    SVT N. Seattle Member

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    Hotwheelz,

    He's trying to get the loads down to around 1,000 fps (speed of sound varies with temperature, atmospheric pressure,& humidity). Those loads are slow, but they are still too fast. It can get dangerous with many powders if you go below the recommended Minimum.
     
  11. johnboy

    johnboy Hillsboro Member

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    Too low C.U.P. may be more dangerous than too much, so must watch pressures....
     
  12. hoghunter

    hoghunter east Texas New Member

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    I have had good luck using a 200gr speer hotcore with 14grs of IMR 4759 seems really accurate out to about 100yds,, winchester primers regular,,. not mag. My 308 DPMS LR cycles these perfectly,, of course I have done other things to make the cycling happen.. Also if you shoot bolt action or single shot, 6.5 grs of Trail Boss with 110 gr v-max works great..