Results 1 to 6 of 6

Thread: .300 Black Out Pistol vs Carbine Gas length tube

  1. #1
    Join Date
    Feb 2015
    Posts
    2
    Feedback Score
    0

    .300 Black Out Pistol vs Carbine Gas length tube

    So, this question my have already been asked and if so, then I apologize. Or this may just be a stupid question and if so then again; I apologize. That being said: I keep reading that one of the ways to ensure that an AR chambered in .300 Blackout on a 16" barrel cycles properly is to have a pistol length gas tube. I get this. It makes sense that there will be more gas pressure closer to the chamber. But, does this not affect the velocity of the round since you are pulling off the gasses that propel the round with around 6" still left for the round to go down the barrel. I feel like if you have a 16" barrel with a pistol length gas tube you have pulled away much of the propulsion but the bullet is still being affected by the friction in the barrel.

  2. #2
    Join Date
    Aug 2011
    Location
    N.E. OH
    Posts
    6,276
    Feedback Score
    0
    Gas port size limits bleedoff.
    I know gas vs bolt velocity tends to be 100-150 fps different iirc.
    I dont think you will see a statistically significant difference between gas system location.

  3. #3
    Join Date
    Nov 2010
    Location
    MI
    Posts
    2,785
    Feedback Score
    21 (100%)
    Gas length won't have a meaningful effect on velocity.

    A pistol length gas is recommended for cycling both subs and supers.

    A carbine is probably the better choice for supers only.
    Black River Tactical
    BRT OPTIMUM Barrels - 16" MPR, 14.5" MPC, 11.5" CQB, 9" PDW
    BRT OPTIMUM-S Barrel - 11.5" CQB Suppressor Gas Drive
    BRT OPTIMUM-S Barrel - 11.5" SB Suppressor, 11.5" SBT 25 Deg Tapered Shoulder Suppressor
    BRT Covert Comps 7.62, 5.56, 6X, 9mm
    BRT MarkBlue Gas Tubes - BRT EXT, EXC and PDW Lengths
    BRT EZTUNE Gas Tubes - CAR and MID
    BRT MicroPin Gas Blocks - .750" & .625"
    BRT MicroTUNE Adjustable Gas Blocks
    BRT CustomTUNE Gas Ports

  4. #4
    Join Date
    Mar 2015
    Posts
    904
    Feedback Score
    0
    Quote Originally Posted by MegademiC View Post
    I know gas vs bolt velocity tends to be 100-150 fps different iirc.
    I am certain it is not that high, and I seriously doubt the difference is reliably measurable....

  5. #5
    Join Date
    Aug 2011
    Location
    N.E. OH
    Posts
    6,276
    Feedback Score
    0
    Quote Originally Posted by lysander View Post
    I am certain it is not that high, and I seriously doubt the difference is reliably measurable....
    I was going off incorrect memory.
    A recent search looks to be 20-30fps.
    It probably varies gun to gun as well.

    Big picture: it’s insignificant

  6. #6
    Join Date
    Feb 2015
    Posts
    2
    Feedback Score
    0
    Quote Originally Posted by MegademiC View Post
    I was going off incorrect memory.
    A recent search looks to be 20-30fps.
    It probably varies gun to gun as well.

    Big picture: it’s insignificant
    that sounds a lot better. 100 -150 ftps was a little concerning since that is 10- 15% of a subsonic load.

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
  •