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Loading Subsonic 308 Win - Seeking Advice

Discussion in 'Ammunition & Reloading' started by Liberty97045, Jul 8, 2015.

  1. Liberty97045

    Liberty97045 Oregon City Well-Known Member

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    I want to load subsonic for 308 and 223, I have done some research and found many different opinions and few recipes.

    I did get some good tips:

    My rifle is set up for the heavier bullets so it makes sense to take advantage of this. I was thinking 200 or even 220.
    1. Does anyone have a recipe for me?
    2. How much risk will I be taking if I work up my own loads? For example, if I took a subsonic recipe with a lighter bullet and substituted a heavier bullet.
    3. If I roll my own, what are the do's and don'ts?

    The 308 is the primary gun. Savage 10 FCP which has a 1:10 - 24" barrel - I will be using a 308 suppressor.

    The 223 is secondary - 20" barrel with same suppressor

    I found this for 308 and 223 using Trail Boss. The problem is they only have data for lighter bullets.
    http://www.loaddata.com/articles/PDF/LD-36 Haviland LR.pdf

    This one is Trail Boss or Red Dot
    http://www.thefirearmsforum.com/threads/anybody-have-308-win-subsonic-load-data.39007/page-3
     
  2. FA9

    FA9 Hillsburrito, ORgun Well-Known Member

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    Check out the Hodgdon website;)
     
  3. ConcreteJungle

    ConcreteJungle Eugene Well-Known Member

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  4. David J

    David J hillsboro Member

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    Trail Boss is temp sensitive. I use IMR 4198 in both 300 BLK and 458 SOCOM. The 300 BLK is loaded with a 220 gr rn. and the 458 is loaded with a 500 gr rn. why use a light bullet for sub sonic the heaver bullet gives better ballistics down range.
     
  5. rick benjamin

    rick benjamin USA, Or, Damascus Secure the drama Silver Supporter 2016 Volunteer

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    According to the NOAA, Speed of sound in FPS
    is dependent on the density of the air...
    is dependent on the temperature of the air.

    99 degrees Fahrenheit = 1158.39 Feet per second = Speed of Sound
    95f = 1154.23
    90f = 1149.02
    85f = 1143.78
    80f = 1138.52
    75f = 1133.23
    70f = 1127.92
    65f = 1122.58
    60f = 1117.22
    55f = 1111.83
    50f = 1106.42
    45f = 1100.98
    40f = 1095.51
    35f = 1090.02
    30 degrees Fahrenheit = 1084.49 Feet per second = Speed of Sound

    No matter how careful you are with someone else's recipe,
    You have no way to prove your results unless...You use a chronograph.

    I own a Chrony F Chronograph, purchased in 1988, and a CED-M2 purchased this year.
    I would not work-up a load without them.
     
    Last edited: Jul 13, 2015
    BlindedByScience likes this.
  6. Certaindeaf

    Certaindeaf SE Portland Well-Known Member

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    Mr. Squirrel is chewing his nut and pondering on that one. I'd go all .310 round ball and a primer.. well, maybe a pinch. lol
     
  7. FA9

    FA9 Hillsburrito, ORgun Well-Known Member

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    With subsonic ammo you work in reverse. Start high, and work your way down.
     
    Certaindeaf likes this.
  8. rick benjamin

    rick benjamin USA, Or, Damascus Secure the drama Silver Supporter 2016 Volunteer

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    How much risk? It depends.
    Substituting ingredients, how would you know the outcome?
    Folks don't have any problem shooting factory ammo in a firearm. They trust it.
    Someone had an M1A last Monday evening at DRRC Dynamics Range.
    Wednesday morning I was policing the range and found pieces.
    2015-07-13 M1A Kaboom a.JPG 2015-07-13 M1A Kaboom b.JPG
    We RSOs discussed how new it looked, couldn't find any more pieces.
    We see a lot more kabooms in the past couple years. This fall we may ban reloads at hunter site in.
     
  9. ConcreteJungle

    ConcreteJungle Eugene Well-Known Member

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    Did that happen with a factory load? Or reloads he was experimenting with?
     
  10. rick benjamin

    rick benjamin USA, Or, Damascus Secure the drama Silver Supporter 2016 Volunteer

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    Not known. No accident report was submitted.
    We know it was a new M1A (.308), shrapnel in the mag box. No blood evident.
    I worry about reloaders that are not safe, and folks who use their product.
    Changing powders, changing bullets. Reloading for their friends, not testing.
    Not chronographing.
     
  11. ConcreteJungle

    ConcreteJungle Eugene Well-Known Member

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    Glad you didn't see an blood, that's a good sign i guess.
     
  12. rick benjamin

    rick benjamin USA, Or, Damascus Secure the drama Silver Supporter 2016 Volunteer

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    This is how I would work this load.
    Consult "Sierra Bullets Reloading Manual"
    Suggested primer Remington 9 1/2 per Sierra book
    Caliber 308, 200 grain Sierra Matchking Hollow Point
    200gr is the heaviest recommended by Sierra book for a 308.
    Powder IMR-4064 36 grains registered 2200 feet per second, per Sierra book.
    Desired velocity at 70 degrees Fahrenheit less than 1127.92 feet per second
    Load 3 rounds at 36 grains, shoot over a chronograph to confirm velocity.
    If velocity confirmed reduce to 35.5 grains and shoot. Record velocities
    Continue to reduce load by .5 grains till recorded velocity nears 1127 fps
    Reduce loads by .1 grains till you attain 1100 fps.
    Good luck
     
    Last edited: Jul 13, 2015
  13. rick benjamin

    rick benjamin USA, Or, Damascus Secure the drama Silver Supporter 2016 Volunteer

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    If you Kaboom a Springfield Standard M1A $1500, A supermatch M1A runs $3500
    If shooting from a bench on sandbags or a rest with body parts behind the trigger,
    Maybe no injuries.
    If triggering with right hand and anchoring the forend with left hand,
    Serious injury to left bicep, elbow, forarm, wrist, hand.
    Wood splinters to the head, upper torso.
    If the receiver-bolt rupture, they may come back into the face.
    Rare, as military guns tend to hold together.
    What might it look like?
    google "gun kaboom injuries" to see blood guts and feathers
     
  14. Liberty97045

    Liberty97045 Oregon City Well-Known Member

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    Please don't
     
  15. Liberty97045

    Liberty97045 Oregon City Well-Known Member

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    So I loaded up some this weekend and they are AWESOME!!!

    I used 10 grains of Trail Boss with a CCI Magnum Primer and a 168 grain HPBT

    Min 1003 fps
    Max 1031 fps
    BP 30.1
    Temp 71F

    I was shooting a Savage 10FCP-SR with a 24" barrel. Without the can it was slightly less noisy than a 22LR from a rifle. WITH the can, freakishly quiet.
     
  16. Certaindeaf

    Certaindeaf SE Portland Well-Known Member

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    It's sight.. not site. good luck with that anyway
     
  17. rick benjamin

    rick benjamin USA, Or, Damascus Secure the drama Silver Supporter 2016 Volunteer

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    There were several kabooms last September.
    Fortunately, no one was hurt.

    I saw a separate thread from Liberty97045, has his own chronograph.