Page 4 of 6 FirstFirst ... 23456 LastLast
Results 31 to 40 of 51

Thread: Colt with 11.5" barrel failing to lock back on last round

  1. #31
    Join Date
    Jul 2010
    Location
    Commonwealth of Pennsylvania
    Posts
    1,359
    Feedback Score
    76 (100%)
    Ok so I ran a bit if ammo through it aside the port was opened to .072. Results are great, the following was all with the H3 buffer with no failures of any kind:
    19 rounds Federal Champion fired one at a time, all caused bolt to lock back.
    19 rounds Federal T223E, 9 fired individually causing three bolt to lock back, 10 fired rapidly.
    150 rounds M855 fired rapidly, slowly, and until bolt lock back.

    I'm very happy so far. I have to get some more .223 to test, especially duty ammo.

  2. #32
    Join Date
    Jun 2007
    Location
    The Free State of Nebraska
    Posts
    5,427
    Feedback Score
    7 (100%)
    Quote Originally Posted by Dr Dues View Post
    I'll be blunt..

    ADCO can't do jack! And when they are questioned about their crappy work, they scratch there heads and say there isn't a problem.

    They need their own "Gunsmithing fail " thread.

    ....ask me how i know.....

    Adco is a slob company.

    I sent them a preban colt lower for a sear block removal, with the understanding it would be tastefully and professionally removed with a mill.

    Instead they cut it out with a dremel tool (they admitted this in email) and left nasty grinding marks.

    I had to fight them for a $100 refund and ended up selling the lower for a $200 loss.

    Never again.
    "Not every thing on Earth requires an aftermarket upgrade." demigod/markm

  3. #33
    Join Date
    Sep 2013
    Posts
    942
    Feedback Score
    0
    would a general test to check if the port is large enough just be loading one round at a time of PMC and seeing if it looks back?

    if so, would it be like an adj gas block that gets an extra click for margin or error and maybe go .02 bigger?

  4. #34
    Join Date
    May 2011
    Posts
    2,114
    Feedback Score
    0
    It's not that simple.

  5. #35
    Join Date
    Aug 2009
    Location
    Arizona
    Posts
    315
    Feedback Score
    1 (100%)
    Quote Originally Posted by jackblack73 View Post
    You should have switched to a lighter buffer, not a heavier one.
    Exactly. Never listen to the person that told you to go heavier.

  6. #36
    Join Date
    Nov 2010
    Location
    MI
    Posts
    3,055
    Feedback Score
    21 (100%)
    Quote Originally Posted by masakari View Post
    Ok so I ran a bit if ammo through it aside the port was opened to .072. Results are great, the following was all with the H3 buffer with no failures of any kind:
    ...
    I'm very happy so far. I have to get some more .223 to test, especially duty ammo.
    You may want to try the H2 buffer next time as well, focusing on feel and sight recovery.
    Black River Tactical
    BRT OPTIMUM HFCL Barrels - Hammer Forged Chrome Lined 11.5", 12.5", 14.5"
    BRT OPTIMUM Barrels - 16" MPR, 14.5" MPC, 12.5" MRC, 11.5" CQB, 9" PDW
    BRT EZTUNE Preset Gas Tubes - CAR and MID
    BRT Covert Comps 7.62, 5.56, 6X, 9mm
    BRT MarkBlue Gas Tubes - BRT EXT, EXC and PDW Lengths
    BRT MicroPin Gas Blocks - .750" & .625"
    BRT MicroTUNE Adjustable Gas Blocks
    BRT CustomTUNE Gas Ports

  7. #37
    Join Date
    Jul 2010
    Location
    Commonwealth of Pennsylvania
    Posts
    1,359
    Feedback Score
    76 (100%)
    Quote Originally Posted by Clint View Post
    You may want to try the H2 buffer next time as well, focusing on feel and sight recovery.
    I did run it with an H1 and there was slightly more sight movement during recoil. The H3 was nice.
    Quote Originally Posted by BillBond View Post
    Exactly. Never listen to the person that told you to go heavier.
    http://www.falfiles.com/forums/showthread.php?t=336766
    Last edited by masakari; 12-29-15 at 14:41.

  8. #38
    Join Date
    Mar 2011
    Posts
    141
    Feedback Score
    1 (100%)
    I'm not meaning to step on anyone's toes here, but I disagree with a lot of the information in this thread.

    The gas on an 11.5 should be smaller than a 10.3, not larger. .070 is Crane spec for 5.56 Nato out of 10.3" barrels. .063 is stock 14.5" Colt Carbine. The 11.5 has more dwell time than the 10.3 and less than the 14.5".

    If the barrel had been chopped to 10.3" with no gas port work, you would have seen more drastic short stroking. Since you only cut to 11.5, you didn't reduce the dwell time as drastic as 10.3" would have, but enough that your rifle was functioning *just* on the verge of reliability (i.e., rifle would cycle but would not lock back on last round).

    My opinion is you went about this all wrong. First off, I would have got the correct gas port spec. Secondly, I would be tuning the rifle for a carbine or H buffer, not *starting* with an H3.

    Something around .067/.068 would have given you a properly gassed rifle with a carbine or H buffer.

    You now have a severely overgassed rifle, and even though you're able to use an H3 to tame it down, you're at the end of your buffer options already and you'll experience faster port erosion and parts wear than necessary.

    ----------

    The 10.3" barrel ends pretty quickly right after the gas port, which means the system only stays pressurized for a very short amount of time. Because of this, the gas port needs to be "enlarged" to insure there's still enough pressure in that short amount of time to cycle the action. The longer you increase the barrel after the gas port, the longer the system remains under pressure and the smaller port is proper for proper functioning. A 14.5"/16" factory Colt for instance will have a port of around .063 from the factory.

    I really don't understand the advice in here saying an 11.5" should have a larger port than 10.3".

  9. #39
    Join Date
    May 2011
    Posts
    2,114
    Feedback Score
    0
    Good post. The .067"-.068" port 11.5" 5.56 does offer many options.

  10. #40
    Join Date
    Sep 2013
    Posts
    942
    Feedback Score
    0
    What about a .069 on a 10.5 barrel?

Page 4 of 6 FirstFirst ... 23456 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
  •