Page 1 of 3 123 LastLast
Results 1 to 10 of 21

Thread: How is a 7.5" barrel with pistol gas for 300BLK?

  1. #1
    Join Date
    Jun 2019
    Location
    NC
    Posts
    72
    Feedback Score
    4 (100%)

    How is a 7.5" barrel with pistol gas for 300BLK?

    My 300 BLK rifle is a 16" right now. I typically only shoot it suppressed with subs, so that's a bit big overall with 8" can. Has a DD barrel right now and have had 0 luck getting good groups with it too. About 2.5" @ 100 yds is best I can get it with any load from a 110gr VMax to a 240 gr MBC. And I tried a ton of stuff in between. This is it's 2nd DD 16" barrel - I returned 1st one for same issue and kind of gave up on it after similar results with replacement.

    Anyway.....the 300BLK has been shelved mostly & want to start getting back into it some more. I want to do an upper for my SBR using a 7.5" barrel which would give me about 15" overall with can. What I don't know is how well pistol gas works with suppressed 300BLK. My current is carbine gas and it runs everything well from supersonic to the slowest subs, suppressor on or off, it just runs anything & doesn't care. Standard carbine buffer, M16 bolt carrier, non-adjustable gas block. Would a 7.5" barrel swap & either straight or pigtail gas tube run as well under those same conditions?

    Also, if anyone knows, I'm thinking I might have to increase the powder charge in my subsonic loads by a tenth or two to get the same velocity from the shorter barrel? Anyone have experience moving to a shorter barrel and needing to adjust the load to stay at the MV you want?

  2. #2
    Join Date
    Nov 2010
    Location
    MI
    Posts
    3,516
    Feedback Score
    22 (100%)
    Any 300 BLK barrel under 16" should use a pistol gas system.

    A very good combo is the 9" pistol gas.

    This allows good function in all 4 modes and was the original configuration AAC launched with.
    Black River Tactical
    BRT OPTIMUM Hammer Forged Chrome Lined Barrels - 11.5", 12.5", 14.5", 16"
    BRT EZTUNE Preset Gas Tubes - PISTOL, CAR, MID, RIFLE
    BRT Bolt Carrier Groups M4A1, M16 CHROME
    BRT Covert Comps 5.56, 6X, 7.62

  3. #3
    Join Date
    Jun 2019
    Location
    NC
    Posts
    72
    Feedback Score
    4 (100%)
    I have the 7.5" on order. I should cancel that & replace with a 9" or is 7.5" acceptable for good function? (especially on suppressed subs, but still want it to work on whatever its fed).

  4. #4
    Join Date
    Jul 2006
    Location
    Oregon
    Posts
    4,630
    Feedback Score
    2 (100%)
    Below 8.5" makes it hard to find a handguard and mount a silencer. 8.5" or 9" runs everything great. Because of the larger bore and faster powder used in the 300, pistol gas is optimal rather than the problem it is in a 5.56

  5. #5
    Join Date
    Oct 2009
    Posts
    921
    Feedback Score
    72 (100%)
    300blk would never be available with a 16” barrel if not for the NFA.

    KB developed the 300blk with AAC and now runs Q. His barrel is 7” with 1:5 twist. They have them in stock at the moment complete with gas block. All reports I’ve seen is that the barrel does a great job. Many reports of hogs taken subsonic at 100-150yds. Look at Discreet Ballistics as examples of effective subsonic hunting ammo.

    https://www.liveqordie.com/products/...rrel-assembly/

    Their sugar weasel has a handguard designed for the forged upper (unlike the honey badger). Not sure when they handguard will be released. I’d look at SLR for handguard lengths since they are a known quality and have every size imaginable.

    If not that, I’d go for the 9” barrel for the benefits stated earlier of of other handguard options.

  6. #6
    Join Date
    Oct 2014
    Location
    Central Texas
    Posts
    2,976
    Feedback Score
    94 (100%)
    Quote Originally Posted by fledge View Post
    300blk would never be available with a 16” barrel if not for the NFA.

    KB developed the 300blk with AAC and now runs Q. His barrel is 7” with 1:5 twist. They have them in stock at the moment complete with gas block. All reports I’ve seen is that the barrel does a great job. Many reports of hogs taken subsonic at 100-150yds. Look at Discreet Ballistics as examples of effective subsonic hunting ammo.

    https://www.liveqordie.com/products/...rrel-assembly/

    Their sugar weasel has a handguard designed for the forged upper (unlike the honey badger). Not sure when they handguard will be released. I’d look at SLR for handguard lengths since they are a known quality and have every size imaginable.

    If not that, I’d go for the 9” barrel for the benefits stated earlier of of other handguard options.
    Interesting thought. I believe that supersonic 300BLK wasn't even on AAC's chalkboard back when they were developing that round. That said, I'm going to build me a "Super 300" mainly because I think it sounds cool and secondly because it's going to be my AK killer. More accurate, more modular, and I don't have to jack with muscle memorizing the 2nd platform. Besides, I just don't like AK's. But I've been chewing on the ballistics of 110gr supersonic ammo. It's got some respectable terminal ballistics even at 400m. I still love my 300 shorty and subs n all. But I'm feeling it. I just can't decide on the barrel. I don't want to do a 16", but maybe a something 12.5-14.5.
    "Texas has yet to learn submission to any oppression, come from what source it may."
    ~ Sam Houston

    “The liberties of our country, the freedom of our civil constitution, are worth defending against all hazards: And it is our duty to defend them against all attacks.”
    ~ Sam Adams

  7. #7
    Join Date
    Oct 2014
    Location
    Central Texas
    Posts
    2,976
    Feedback Score
    94 (100%)
    Quote Originally Posted by CMV View Post
    I have the 7.5" on order. I should cancel that & replace with a 9" or is 7.5" acceptable for good function? (especially on suppressed subs, but still want it to work on whatever its fed).
    OP - I'd go with a bit of a longer barrel myself. Is there a reason you want to do a 7.5?
    "Texas has yet to learn submission to any oppression, come from what source it may."
    ~ Sam Houston

    “The liberties of our country, the freedom of our civil constitution, are worth defending against all hazards: And it is our duty to defend them against all attacks.”
    ~ Sam Adams

  8. #8
    Join Date
    Oct 2012
    Location
    Twin Cities
    Posts
    1,052
    Feedback Score
    93 (100%)
    I have an original AAC 9” upper and Ballistic Advantage 8.3” Hanson. The BA is lighter, but I would not part with either.

    The BA is on sale right now. https://ballisticadvantage.com/8-3-i...um-barrel.html
    “ When I comes to modern politics, I think the inverse of Hanlon's Razor applies...In other words, "Never attribute to stupidity that which is adequately explained by malice." - Kerplode

  9. #9
    Join Date
    Jul 2006
    Location
    Oregon
    Posts
    4,630
    Feedback Score
    2 (100%)
    Quote Originally Posted by RobertTheTexan View Post
    I believe that supersonic 300BLK wasn't even on AAC's chalkboard back when they were developing that round.
    They developed the subsonic that cycles closer to supersonic.

    Longer supersonic bullets like UMC and blacktip that stack well in 5.56 mags.

    Supersonic performance was always part of the picture.

  10. #10
    Join Date
    Nov 2010
    Location
    MI
    Posts
    3,516
    Feedback Score
    22 (100%)
    And then Magpul came along and developed a mag that works with nearly every 300BLK load without binding.

    https://www.magpul.com/products/pmag...uctColor=VO343
    Black River Tactical
    BRT OPTIMUM Hammer Forged Chrome Lined Barrels - 11.5", 12.5", 14.5", 16"
    BRT EZTUNE Preset Gas Tubes - PISTOL, CAR, MID, RIFLE
    BRT Bolt Carrier Groups M4A1, M16 CHROME
    BRT Covert Comps 5.56, 6X, 7.62

Page 1 of 3 123 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •