Results 1 to 20 of 20

Thread: 300 blackout not cycling

  1. #1
    Sergeant
    Follows
    0
    Following
    0

    Join Date
    Dec 2005
    Location
    possumneck, ms
    Posts
    779

    300 blackout not cycling

    I have a AAC 300 blackout upper (16") on a standard Rock River lower with a A2 stock. I have the bolt carrier group well lubed running southwest subsonic 220's. I have tried a pmag and a rock river 20 round mag and it still fails to cycle. Do I need to change buffer tube or springs? Thoughts or ideas?
    Thanks
    AIM SMALL.... MISS SMALL

  2. #2
    Gunny Sergeant
    Follows
    1
    Following
    0

    Join Date
    Oct 2007
    Location
    Central Ohio
    Posts
    1,402
    I'd try different ammo if you can. Is it a pistol or carbine length gas system? How is it not cycling? Are you using a can?
    Last edited by mscott; 04-01-2013 at 08:05 PM.

  3. #3
    Sergeant
    Follows
    0
    Following
    0

    Join Date
    Dec 2005
    Location
    possumneck, ms
    Posts
    779
    It's a factory standard 16" AAC complete upper. I have also tried remington subs. A few will feed other times it just fails to feed the round. It could be an issue with the mag or mag lip as well. Very new to shooting subs in a ar platform. I know very little about gas guns
    AIM SMALL.... MISS SMALL

  4. #4
    Sergeant
    Follows
    0
    Following
    0

    Join Date
    Jun 2007
    Location
    Tallahassee, FLORIDA
    Posts
    402
    tell us what direction the brass ejects from the rifle. If 1-2 o'clock, then bad. If 3-4 o'clock, good (or at least better).

  5. #5
    Sergeant
    Follows
    0
    Following
    0

    Join Date
    Dec 2005
    Location
    possumneck, ms
    Posts
    779
    3 to 4. 4 mostly. What does that tell you?
    AIM SMALL.... MISS SMALL

  6. #6
    Gunny Sergeant
    Follows
    1
    Following
    0

    Join Date
    Oct 2007
    Location
    Central Ohio
    Posts
    1,402
    Sounds like a good ejection pattern, so I'm guessing the powder burn rate just isn't enough to cycle the gun. I wonder if they are using H110 for that ammo? Are you running a suppressor? My 9.5" pistol gas will run subs without a can, but my 16" carbine gas is a little more finicky. I'm also reloading using A1680 powder.

  7. #7
    Gunny Sergeant
    Follows
    0
    Following
    0
    swammo's Avatar
    Join Date
    Jul 2010
    Location
    Mesa, Arizona
    Posts
    1,616
    We use AA 1680 as recommended by AAC, and test fire each lot in the same 16" upper that you have with Pmags. AAC advises the use of a standard carbine buffer, a heavy buffer may be your problem.

    Give us a call at the shop, and ask to talk to me, and we'll figure this out.

    Thanks,

    Mike


    Sent from my iPad using Tapatalk HD

  8. #8
    Private
    Follows
    0
    Following
    0

    Join Date
    Sep 2009
    Posts
    76
    Are you running a can? Does that upper have an adjustable gas block? I know some set ups are intended to run subsonic suppressed only.

  9. #9
    Sergeant
    Follows
    1
    Following
    0

    Join Date
    Apr 2010
    Location
    Northern Virginia, USA
    Posts
    345
    Rifle length A2 stock --- I think this may be your issue -- pretty much all .300 testing I have seen has been on carbine lowers with standard weight carbine buffers
    Kevin S. Boland

    Director of Military Operations
    Knight's Armament Company
    701 Columbia Blvd.
    Titusville, Fl 32780
    1(321)607-9956
    kboland@knightarmco.com

    www.knightarmco.com

  10. #10
    Sergeant
    Follows
    0
    Following
    0

    Join Date
    Dec 2005
    Location
    possumneck, ms
    Posts
    779
    I do have it on a A2 stock. I removed the rifle buffer and put a carbine buffer in. Fired 5 rounds in the back yard and seems to work. When the rain stops I will take it out and fire a magazine and see how it works for real. 5 in the ground in the back yard is only a tease.
    AIM SMALL.... MISS SMALL

  11. #11
    Private
    Follows
    0
    Following
    0

    Join Date
    Feb 2013
    Location
    Portland, OR
    Posts
    19
    Check your buffer spring as well. Make sure it is a "TRUE" milspec.........I had an issue and it was the BCM buffer spring I was running.

  12. #12
    Gunny Sergeant
    Follows
    1
    Following
    0

    Join Date
    Oct 2007
    Location
    Central Ohio
    Posts
    1,402
    I don't think you want to run a carbine buffer in an A2 stock without a spacer. There is a reason buffers are a certain length.
    You can lighten up your A2 buffer by taking it apart and replacing the steel weights with aluminum weights.

  13. #13
    Sergeant
    Follows
    0
    Following
    0

    Join Date
    Dec 2005
    Location
    possumneck, ms
    Posts
    779
    Listening and learning. Have a carbine kit inbound
    AIM SMALL.... MISS SMALL

  14. #14
    Private
    Follows
    0
    Following
    0

    Join Date
    Feb 2012
    Location
    North TEXAS
    Posts
    98
    i think the subs were designed to run w/ a suppressor. are you running it suppressed? supers will probably cycle it. but i agree w/ everyone else, it's the buffer.

  15. #15
    Sergeant
    Follows
    0
    Following
    0

    Join Date
    Dec 2005
    Location
    possumneck, ms
    Posts
    779
    Got the suppressor. The whole thing is no good without it IMO. Carbine stock kit coming today or tomorrow. Hopefully she will cycle rapidly
    AIM SMALL.... MISS SMALL

  16. #16
    Sergeant
    Follows
    0
    Following
    0

    Join Date
    Apr 2013
    Location
    Lubbock, TX
    Posts
    293
    My buddy has a Blackout and tried everything, we finally put a JP Buffer in it because its "self adjusting" and sure enough it worked, and on another note it sounds like butter when you pull back the charging handle

  17. #17
    Ron
    Ron is offline
    Private
    Follows
    0
    Following
    0

    Join Date
    May 2013
    Posts
    1
    I'm having a problem with my 300 blackout as well, i'll fire 5 rds. but the bolt does not lock back, it cycles on a empty mag. i have a 16" black hole barrel carbine length gas system blow back. carbine stock wth a standard carbine buffer and buffer spring, sometimes the bolt will lock back but most of the time it dose not. plus i'm using a jp interprise adjustable gas block.
    i am stumped !!this gun is giving me fits.
    is the gun over gasing or is the buffer to heavy? what would be a god light buffer and what buffer spring would work?
    please hepl!!!

  18. #18
    Gunny Sergeant
    Follows
    0
    Following
    0
    The Lawn Ranger's Avatar
    Join Date
    Oct 2009
    Location
    Northern Kentucky
    Posts
    1,174
    I have a 10.2" Noveske that won't lock open after the last round with some factory ammo types.

    Loading my own solved this.

    Mine is without adj. gas block
    "No great thing is created suddenly" —Epictetus (A.D.200)

    "To alcohol: The cause of, and solution to, all of life's problems." Homer (A.D. 2007)


  19. #19
    Private
    Follows
    0
    Following
    1
    gaphighpower's Avatar
    Join Date
    Jan 2012
    Location
    Royse City Texas
    Posts
    90
    I had similar problems during my build.

    My build:
    Wilson Combat 18” upper – straight gas, not adjustable
    Stiller Precision PredatorXT lower
    Standard milspec receiver Extension Kit – standard buffer
    Magpul CTR Mil Spec Stock

    I reload my 220s:
    Sierra 220 HPBT match
    9.0g LilGun, in mixed brass

    I run a SHARK suppressor ALL THE TIME with 220s.

    Everything I shot under 220g runs great with the above specs (with or without suppressor), but when I started shooting the 220’s the problems started.

    The two modifications I made to run 220’s smoothly:

    1) I used a shorter buffer spring (see pic) 10.75” vs. 11”
    2) Check your mag(s). Load 3-4 rounds. Notice the ogives’ and large footprint of the 220 to be radical for a magazine designed to shoot .223 bullets. Press down into the follower. Do you notice binding when you push down? Can you manually push a round out (feed) with the next round rising smoothly and correctly into the lips and not binding in the mag? I found binding in all the mags I had – plastic and metal. This caused the bolt group to ‘ride over’ a round that would not rise to the correct height in the mag. I got out the dremel tool and removed the ‘rib’ portion of a metal 20 rounder (see pic). The 220s feed butter smooth now and I have smooth function from first round to last.

    Of course, YMMV.

    Hope this helps,
    gap
    Attached Images Attached Images

  20. #20
    Sergeant
    Follows
    0
    Following
    0

    Join Date
    Jul 2011
    Location
    MD
    Posts
    571
    same problem here with suppresor, I cut 3 coils off the buffer spring and now it runs perfect! cycles and locks back every time. I also have a MGI heavy buffer and I swear when I added it the gun got quieter. Does that make since?
    Great minds discuss ideas, average minds discuss events, small minds discuss people.
    1/20/17 Change is coming