Subsonic. 308 ammo that works in semiauto rifle

Discussion in 'The Ammo & Reloading Forum' started by Praedor, Jun 8, 2019.

  1. Praedor

    Praedor New Member

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    I've developed a load that is subsonic and cycles the action in my DSA SA58 FAL rifle. The rifle is a carbine, 16" barrel, full length gas system. I've tested this load over multiple rounds and it works. I don't have crono data yet, am simply going by ear (no supersonic crack). I've tried it with and without a silencer.
    The load: *** Varget and then a**** gr Trail Boss powder on top. This fills the cartridge to the bottom of the neck and produces a lightly compressed load. No signs if pressure at all. The bullet I'm using is Hornady 180 gr SP Interlocks (flat tail/base). This load has also worked with other bullets I've tried like Hornady 168 gr A-max. I've been using magnum primers to get some extra oomph but will switch to normal primers when they're used up.
    Starting off I found it was impossible to load enough Trail Boss into the cartridge to go supersonic or cycle the action (all the way to the rim and compress loading the bullet). I then started with *** Varget and *** Trail Boss and kept incrementing the Varget by ***, reducing the Trail Boss to always end at the base of the case neck. The final load that worked well for me was what I posted above.
     
    Last edited by a moderator: Jun 10, 2019
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  2. JRK57

    JRK57 Well-Known Member

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    That’s very interesting. What kind of accuracy are you getting?
     
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  3. shootbrownelk

    shootbrownelk Well-Known Member

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    Mixing Powders?
     
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  4. LDBennett

    LDBennett Well-Known Member

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    While experimenting with reloading is fun for some, it is not without its dangers.

    Mixing powders is not recommended by any reloading manual I own (I own at least a dozen of or more). Loads different than published reloading manuals includes risk of gun and personal damage.

    Starting low on the energy scale with the load (if below reloading manuals starting loads) can get the bullet stuck in the barrel, missed by the shooter, and subsequent bullets packing into the barrel. This ruins the barrel, usually, and sometimes worse.

    I have no problem with a reloader deviating from published loads but don't shoot near me and don't come back complaining about damage to your gun if things go wrong. Reloading can be dangerous if you don't follow reloading manual recommendation. But we all get to choose!

    BE SAFE not SORRY.

    LDBennett
     
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  5. Praedor

    Praedor New Member

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    Absolutely, and I agree. I was leery of trying it but when I found that no amount of Trail Boss was a problem, and then knowing that a compressed Varget load was safe as well, I opted to try the unorthodox and unrecommended mixed powder load. I started very low with the Varget until I was comfortable that there were no pressure signs (I also checked the barrel after every shot until I was sure there were no stuck bullets, or I was definitely seeing them impact downrange).

     
    Last edited: Jun 10, 2019
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  6. LDBennett

    LDBennett Well-Known Member

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    Praedor:

    you apparently knew the possible bad consequences and avoided them. I just wanted to point out to the unknowing new reloader that your approach had a lot of risk in it. Even with your cautious development plan and execution, I would never recommend it to anyone else or even try it myself. Over the years I have been burned by a few reloading mistakes (fortunately with no bad consequences!) and learned to follow the reloading manuals. I highly recommend to others to do the same but everyone gets to do their own thing and take their own risks. I certainly would not want to recommend anything that resulted in damaging a gun or inflicting personal harm. More than one person has "experimented" and paid the price.

    LDBennett
     
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  7. Don Fischer

    Don Fischer Well-Known Member

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    Determining pressure by sound? Gotta be kidding. I'd strongly recommend everyone staying away from mixed powder loads. No clue at all what will happen till you pull the trigger, then its to late. This is something that should never show up on here for sure as can be some novice is gonna try it!
     
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  8. carver

    carver Well-Known Member Supporting Member

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    Welcome to the forum! I've edited your post, for safety reasons, to remove the load you've worked up. If someone here is interested they can PM you for the load. Have you given any thought to getting a patent, and then see if any of the bullet companies would like to produce it.
     
  9. Praedor

    Praedor New Member

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    WHAT?! Where did I say that? I said I was basing my conclusion that it was still SUBSONIC on sound. I know a supersonic crack when I hear one. I haven't heard one so it is subsonic (at the temp and elevation that I live at). I look for PRESSURE signs by checking my cartridge and the primer. No flattened primers, no dimpled primers, no bulging cases. Sheesh.

    There is NO WAY to get overpressure from a full .308 case with Trail Boss. It's IMPOSSIBLE. Filling the cartridge to the actual rim of the case and seating a bullet on top will still not cause pressure signs. It's still subsonic like that too. I have ZERO fear from Trail Boss. I started low with Varget and worked up, checking my cases for any signs of pressure each time, as well as ensuring no bullet was stuck in the barrel. Now that I've fired off a mag full of subsonic loaded as I mentioned and seen zero signs of pressure, I am confident in my load. I don't even get pressure signs from a case load of Varget (compressed load) so I am not concerned much with pressure being a problem with a mix of the two, especially when the amount of Varget used is so small.

     
  10. Praedor

    Praedor New Member

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    I haven't checked for that as yet. I'll be looking at 100 yds and lower. I was out in a corn field and simply seeing the bullet impacts in the dirt about 70 yards away. I was mainly interested in a load that cycled the action AND was subsonic. All I have for accuracy right this moment is impacts on the ground were clearly visible around where my fixed sights were aimed...I'll get ACTUAL data next, even try my cheap crono.

    Yup. And I know. A naughty, but I did it anyway and it works - the amount of Varget used is low and Trail Boss is virtually impossible to over-pressure with by itself (literally) in a .308.
     
  11. CCHolderinMaine

    CCHolderinMaine Garandaholic Supporting Member

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    Just out of pure curiosity. What are you planning to do with subsonic .308 rounds?
     
  12. Praedor

    Praedor New Member

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    For me, it's just fun and there was the challenge. I've read a lot of threads about people asking about .308 rounds that will work in a semiauto rifle and it was generally a given that there was no such beast. People were suggesting a different caliber like 300 Blackout instead. I wanted to see if I could make subsonic work in my semiauto...and I did it. I can also fire away with a silencer in the back 40 and not scare the crap out of my horses or dogs (they don't care for the muzzle blast of normal rounds). A lot of folks like subsonic rounds for fairly close-in hunting (mostly varmints, I gather, I don't hunt) with or without a silencer. It is much more "pleasant" on the ears.
     
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  13. Kvasir

    Kvasir Well-Known Member

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    I would think an easier method to slow the round would be to use a heavier bullet.
    I've been making sub-sonic 300 Blackout rounds by using 230 gr cast .109 bullets sitting on an H110 charge. They work just fine.
    You are dealing with a bigger case, but using Trail Boss should take care of that.