Page 4 of 4 FirstFirst ... 234
Results 31 to 37 of 37

Thread: Has anyone seen ammunition testing done with very short barrel 5.56?

  1. #31
    Quote Originally Posted by TGS View Post
    FBI3T, though I'm sure there's M855 floating around in certain locales still.

    ETA: Just to be clear we're using 10.3" and 14.5" carbines, not 7.5". We T&Ed a few 7.5" guns a couple years ago but I don't think it went anywhere.
    Is it the 5.56 or .223 version? Federal seems to make a variety of different T3 loads for various LE contracts. Aside from the XM556FBIT3 that's 5.56, I've also seen XM556FBIT3M (.223 pressure), XM223T3HSPB (.223), and XM556SBCT3 (5.56).

  2. #32
    Member TGS's Avatar
    Join Date
    Apr 2011
    Location
    Back in northern Virginia
    Quote Originally Posted by DiscipulusArmorum View Post
    Is it the 5.56 or .223 version? Federal seems to make a variety of different T3 loads for various LE contracts. Aside from the XM556FBIT3 that's 5.56, I've also seen XM556FBIT3M (.223 pressure), XM223T3HSPB (.223), and XM556SBCT3 (5.56).
    The stuff I have is XM556FBIT3M, with 223 listed below that.

    No idea why they don't just call it XM223FBIT3.

    We very well might have various forms to the FBIT3 floating around depending on what year it was bought.

    What's different about the HSPB and SBCT3?
    "Are you ready? Okay. Let's roll."- Last words of Todd Beamer

  3. #33
    Quote Originally Posted by TGS View Post
    The stuff I have is XM556FBIT3M, with 223 listed below that.

    No idea why they don't just call it XM223FBIT3.

    We very well might have various forms to the FBIT3 floating around depending on what year it was bought.

    What's different about the HSPB and SBCT3?
    Thanks!

    Regarding the differences among those various SKUs, I don't know anything beyond what I've been able to piece together from publicly available gov contracts and a few tidbits from other sources.

    The HSPB load was in use by ICE. I would bet it's the same as the .223 spec FBI load, just with a different SKU due to packaging (instead of 20rd boxes, it's loaded on stripper clips in 30rd cardboard sleeves, 900rds to a case if the TargetSports description is accurate.)

    I can't find reference to SBCT3 in any official sources, but I've seen speculation that it's a 5.56 spec load optimized for the 11.5" guns that the FBI has standardized on (I guess SBC could stand for "short barreled carbine"?) or just a different SKU for non-FBI sales.

  4. #34

    4.5" to 5" 5 56 AR ballistics

    Does anyone have any resources on the effectiveness of loads like Gold Dot or Barnes TSX out of barrels as short as 4.5"? I would assume that there would be little to no effective expansion, but I'm curious if there has been any documented testing of barrels that short. Other than getting the most compact package possible but staying in a mainstream calber I'm just not seeing the benefits, yet there are several companies now offering such things.

  5. #35
    Quote Originally Posted by MandoWookie View Post
    Does anyone have any resources on the effectiveness of loads like Gold Dot or Barnes TSX out of barrels as short as 4.5"? I would assume that there would be little to no effective expansion
    The estimated 4.5" barrel velocities and expansion thresholds for most loads do not look very encouraging.

    https://www.ar15.com/forums/ar-15/Up...el-/16-721162/


    http://ballisticsbytheinch.com/223rifle.html

  6. #36
    Quote Originally Posted by Velo Dog View Post
    The estimated 4.5" barrel velocities and expansion thresholds for most loads do not look very encouraging.

    https://www.ar15.com/forums/ar-15/Up...el-/16-721162/


    http://ballisticsbytheinch.com/223rifle.html
    Yeah, even at the muzzle it looks like most loadings would fail, making it an exercise in sound and fury over substance.

  7. #37
    Site Supporter OlongJohnson's Avatar
    Join Date
    Mar 2015
    Location
    "carbine-infested rural (and suburban) areas"
    I know you'll see it in the other thread where you posted the same questions, but for people coming along later...

    https://pistol-forum.com/showthread....35#post1062735
    .
    -----------------------------------------
    Not another dime.

User Tag List

Posting Permissions

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