Sub-sonic 5.56 that will cycle

Discussion in 'Firearms' started by Seacowboys, Aug 1, 2017.

  1. Seacowboys

    Seacowboys Senior Member Founding Member

    Does anyone have load data on a round that will cycle an AR or M16,1:9 10.5 w/suppressor? I have tried various loads with no luck but have heard of loads that will cycle and wonder if it BS or a magic bullet?
    sec_monkey likes this.
  2. 3M-TA3

    3M-TA3 Cold Wet Monkey

    Unless you have an adjustable gas system or can find the right combination of buffer spring and weight not sure if it's possible. 300 BO has been done, though not by me. If I went subsonic I'd go with the 300 BO to get the heavier bullet mass anyway.
    snake6264 and sec_monkey like this.
  3. Seacowboys

    Seacowboys Senior Member Founding Member

    I have a .300 Blackout suppressed with a 10.5 barrel that functions flawlessly with no modifications, was just wanting to see if a .223 could be made to cycle
    sec_monkey likes this.
  4. Tully Mars

    Tully Mars Metal weldin' monkey

    One guy I know back home got his to function by cutting a couple coils off the recoil spring. I don't know the load. It used a 55grn FMJ and Win 748 powder. I can try and get ahold of him if you'd like. Sorry I can't help more.
    sec_monkey likes this.
  5. apache235

    apache235 Monkey+++

    sub-sonic .223 will put you about the same as a .22 LR so I wouldn't even try. 300 BO is the way to go. Even the super-sonic rounds aren't that noisy - noisy being a relative term.
    sec_monkey likes this.
  6. Altoidfishfins

    Altoidfishfins Monkey+++ Site Supporter+

    Apache brings up a good point. If you're going to try subsonic .223, why not look into a .22 LR conversion using standard velocity rounds?
    snake6264 and sec_monkey like this.
  7. enloopious

    enloopious Rocket Surgeon

    I like silencer better. It sounds better than suppressor, which only sounds like its trying to keep quiet and not actually doing it. it pisses off the elitists.
    sec_monkey and Altoidfishfins like this.
  8. RouteClearance

    RouteClearance Monkey+++

    Never tried reloading for something like this, but you would need a slow burning propellant that would have a high port pressure, but don't know if there is any published load data for such a load due to SEE or Secondary Explosion Effect because of a powder that produces plenty of port pressure with minimal chamber pressure.
    sec_monkey likes this.
  9. Altoidfishfins

    Altoidfishfins Monkey+++ Site Supporter+

    Hodgdon Reloading Data Center
    55 gr projectile with Clays powder, MV 1060 FPS - doubt if that will cycle the action with only 3700 CUP
    sec_monkey likes this.
  10. Seacowboys

    Seacowboys Senior Member Founding Member

    Everybody that says it puts you in the same class as a .22LR is not doing the math, you got to look at ft lbs of energy and point of impact. All the "experts" on say the same thing until someone points out the fallacy by working the math for them. load an 80 grain projectile and push it at 1050fps an it just hits harder than a 40 grain pill. Even a 55 grain pill hits harder but not much.
    Witch Doctor 01 and sec_monkey like this.
  11. sec_monkey

    sec_monkey SM Security Administrator

    62 gr. will do more damage than 40 gr. plus it should behave a lot better than .22LR ;) ;) even at low fps

    an adjustable gas sys is probably the best solution like 3M said :) (y)
    Tully Mars likes this.
  12. sec_monkey

    sec_monkey SM Security Administrator

    .458 SOCOM which was designed for the kind of use yer lookin for, would be a better choice than .300 AAC

    ARs in .458 SOCOM are available

    typical weights range from about 250gr to 600gr.

    the round was specifically designed to be 100% M4 compatible and thus is AR compatible
    Last edited: Aug 2, 2017
  13. oil pan 4

    oil pan 4 Monkey+++

    About the slowest you can go and still cycle is around 2,500fps.
    I think I used around 18 to 20gr of RE25 with an M193.
    Yeah 5.56mm, semi-auto and sub sonic just don't go together.
    It's like trying to make an off road towing prius.
    Altoidfishfins and sec_monkey like this.
  14. Witch Doctor 01

    Witch Doctor 01 Mojo Maker

    @Seacowboys Have you considered checking the buffer spring and buffer instead of the round? in a 10.5 barrel with a 4" suppressor you may want a heavier buffer (H2, A5 or STT2 buffer of your choice?) to give you enough weight to cycle the weapon reliably. Then work on your load....

    Last edited: Aug 4, 2017
  15. Kingfish

    Kingfish Self Reliant

    I think the point of a sub sonic 5.56 is to NOT create more damage. I looked pretty hard at this in my search for the ultimate survival rifle and came up short. I wanted to use a 5.56 for little game like squirrels and small birds. I failed to find any rounds that would not destroy small game. On the other hand a .22 long rifle can be much more versatile as in hyper rounds that travel at up to 1600/1700 fps can be used for game like deer. A bolt action .22 can shoot any .22 rimfire round from little shorts, sub sonics to hyper rounds like the CCI Stinger and the Aquila . For hunting I found the .22 Bolt action or single shot rifles to be far more versatile. I love my AR-15 rifles but I only hunt Coyotes with them. I also use them for defense for obvious reasons like weight and number of rounds I can carry. Now bolt action .223 or single shot? yes you can down load one to shoot like a .22 RIMFIRE. But why do that? much more expensive per round.
  16. oil pan 4

    oil pan 4 Monkey+++

    If you can download loan .224 bullets I found that M193 tends not to fragment below 1,700fps.
    An M193 at 1,600 to 1,700 fps does way more damage than any 22lr round even hollow points and it doesn't blow most small game to shreds.
  17. Kingfish

    Kingfish Self Reliant

    Still over kill for small game and much more expensive per round. Not to mention the changing of optics ( if you use them like I do) My rifles are sighted in at 100 yards using standard 55 grain ball and why would I want to mess with that? A .22 rim fire will handle your small game needs easily. and doesn't blow any small game to shreds. To make a .223/5.56 SHOOT SUB SONIC doesnt make any sense to me. I guess that is just my take on this topic.
    oil pan 4 likes this.
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