Anybody have .308 Win. Subsonic Load Data?

Discussion in 'The Ammo & Reloading Forum' started by bluesea112, Sep 6, 2007.

  1. bluesea112

    bluesea112 Active Member

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    I thought I had seen a thread on .308 Win. Subsonic loads, but my search came up empty.
    Does anybody have load information for loading the .308 Win. subsonic?

    Thanks,

    Bluesea112
  2. AngelDeville

    AngelDeville New Member

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    It seems to me my Lyman book has data on 100-110gr lead plinkers, but I have to find my book....

    What kind of bullet are you thinking of?
  3. bluesea112

    bluesea112 Active Member

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    I would prefer to load a jacketed bullet. However, if the load data is for regular lead I will use it. I appreciate you looking that up for me AngelDeville.
  4. inplanotx

    inplanotx New Member

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    A .308 is not meant to be subsonic. To be subsonic you would need to be under 1,050 fps. Loading that low would mean lots of air space in the case instead of powder. I would guess that a secondary explosion would blow up the gun because of it.

    IPT
  5. AngelDeville

    AngelDeville New Member

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    I found Data in my Speer book for 100 grain Speer lead bullets part# 1805.
    But the Velocity on these is still close to and exceeding 3000fps.

    And my Lyman book yeilded a 113gr Cast bullet still over 1540fps

    My plinkers are 150grain SP, at 2500fps.

    the lowest velocities I found in my books are over 2200 FPS for the jacketed bullets.


    even if data is found I wouldn't use jacketed bullets for lower velocities, if a jacket separates in the barrel your next shot could be costly...

    buy at least 2 books if you don't already have some and cross reference the data between the 2 books, and never go below the minimums.

    If you do decide to use data found online, still reference your books, you never really know who is posting data, and a miscalculation or typo could be dangerous.
  6. bluesea112

    bluesea112 Active Member

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    Thanks for the information guys. I didn't see any loads listed in my manuals for .308 Win., so that is why I had asked if anybody had the subsonic information. I to thought that .308 Win could not be loaded subsonic until recently. I was browsing Cheaper Than Dirts website and they are selling subsonic .308 Win. However, the price is out of this world. In reference to InPlano's comment, I am curious about how much empty space is left in their cartridge. I wish I knew what powder they are using for their loads. If I can find a spare minute or two, I might call their retail store and ask a few questions. If I can find out anything about their subsonic cartridges, I will be sure to post it.
    Thanks again for your replies.
  7. pasquot

    pasquot New Member

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    I was looking for the same info. What i found was an article by c e harris. It;s called the load. It can be used with any medium cartridge. aka .30cal The standard load is 16grains of 2400 in a 308, 3006, 30cal russian, 303, etc. You can use either lead or fmj. velosity averages about 1600 fps.

    I don't know now where i found the article but it is availabe online. Suggest a search for c e harris or the load. etc until you find the article. Be advised, the old load was 13grains of red dot. Unknown why he changed it.
  8. Popgunner

    Popgunner New Member

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    The only thing I can think of that a sub-sonic load would be good for would be shooting thru a silencer. There are "gallery" loads for the .308 but they won't be subsonic. The weakest load I've loaded for my .308s has been 5 grains of Unique with the Speer 100 grain plinker. An absolute pipsqueek of a load but I'm not sure it's sub-sonic.
  9. JLA

    JLA Well-Known Member

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    try a relatively fast burning pistol powder that is not position sensitive and not double base...(like hodgdon titegroup) and cross reference data for bullet weights that match the ones you intend to use. you should be able to "wildcat" up such a load without much risk of personal injury. but be very very careful in your powder selection. double base propellants tend to explode if there is too much dead space in the case.
  10. bluesea112

    bluesea112 Active Member

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    Thanks for the comments guys. I am not experienced enough with reloading to play around with different loads. In reference to one of the earlier comments, a bullet has to stay under 1150 ft per second to be sub sonic. Any speed over that will generate a sonic "crack" and make the bullet "wobble" as it enters and exits the sound barrier. Neither of those phenominas are desireable.
    Here is the situation:
    I have figured out that I can open the window about 3 inches in my back bedroom for the bullet to go through. If the bullet does not break the sound barrier, the bedroom itself acts as the suppressor and muffles the sound enough that the shot cannot be heard outside. I have run about 5000 rounds of sub-sonic .22 through that 3" window opening, and I am starting to get bored with the .22. I live outside of the city limits but I own an RV park. It is perfectly legal to shoot a gun out here in the country, but gun shots tend to piss off my guests. The nearest range is about 1 hour drive from here, and I get an itchy trigger finger between trips to the range.
    Since a bedroom does not attach to the muzzle of my gun, I don't have to pay the jack booted terror squad $200.00 or even come within gagging distance of the air they breath.
  11. Popgunner

    Popgunner New Member

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    With the rifling twist your .308 has you may not be able to stabilize bullets traveling that slow. What if the supersonic crack happened anyway inside your room? It may be worth a try to see how loud it is outside.

    E
    what was the situation with those two guys back east that were riding around in a car with a big trunk shooting people thru a hole in the trunk with a 223 Bushmaster? seems like that deadened the sound. I can't remember the story.
  12. bluesea112

    bluesea112 Active Member

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    I tried your idea Popgunner. I had my girlfriend stand outside at the opposite end of the house so she could tell me how loud it was. She said it sounded like a crane dropped a bunch of steel from the top of a 5 story building onto a concrete slab. I guess the sound barrier crack must continue behind the bullet, so you hear it no matter where you are standing along the bullet's path. That was the first time I had ever shot a large caliber rifle inside a closed room. I'm surprised I didn't get a nose the bleed from the pressure. It was enough to blow the curtains down. Thank God there were no powder burns on them or I would have never heard the end of it.
  13. Popgunner

    Popgunner New Member

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    As long as you're having fun:D
  14. bluesea112

    bluesea112 Active Member

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    I wonder if I could pack bentonite (clay) (aka:catlitter) into the cartridge to take up space. That way I could use a reduced load of IMR 4895 without there being too much extra space left over in the cartridge. When bentonite is rammed, it packs down tightly and is as hard as concrete. After ramming it, I could use a 1/32" drill bit to bore a hole through to allow the primer to ignite the powder..
    Anybody know of a reason packed bentonite would not work, or any other reason not to try this? The last thing I want to do is mess up my rifle, so I want to experiment safely.


    bluesea112
    Last edited: Oct 21, 2007
  15. Popgunner

    Popgunner New Member

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    Not a good idea. Good chance of ruining your barrel.

    If you want to have a low noise load try 10 grains of unique powder with whatever bullet you have. Cast lead works fine. Very quiet. Fillers are generaly frowned upon.
  16. bluesea112

    bluesea112 Active Member

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    Just the info I was looking for. Thank you Popgunner.
  17. goodstuff412

    goodstuff412 New Member

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    8-10 Grains of Trailboss cowboy action pistol powder. 168 Gr SMK BTHP will produce SAFE, accurate and subsonic results. The powder is bulky and leaves less than 30% empty case volume. Velocity varries with powder charge of course. I have found that humidity and temp are a huge factor. Sonic crack occurs at 1050 and I like to keep mine right at 1000 fps to build a +/- 50fps "crack factor" depending on temp and humididty.

    Good luck
  18. treeclimber

    treeclimber New Member

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    I have been using 8.5 grams of Shotgun powder and yes there is alot of empty space in the cartridge. My barrel has a 1 in 10 twist and I'm using a 160 grain 3060 projectile its nice and long which should help with travel through the air. I haven't been to the range with them yet.
  19. zkovach

    zkovach Active Member

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    I have zero to add here however i am wondering what purpose is there to have a subsonic load????
  20. Alpo

    Alpo Well-Known Member

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    Quiet.

    You have two distinct sounds when you fire a rifle. You have the "BOOM" of the powder going off, and the much louder, sharper "CRACK" of the bullet breaking the sound barrier. If you can get it subsonic, you not only have no CRACK, but the boom is much quieter, since there is less powder being used.

    I found loads, using a 190 grain cast bullet, that started at 1140. Still supersonic, but getting down there.
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