.223/5.56 is less suited for short barrels than other chamberings: myth?

Discussion in 'Auto & Semi-Auto Discussion' started by LethalJustice, Jul 21, 2010.

  1. LethalJustice

    LethalJustice New Member

    I am getting ready to buy a 16-18" Robinson XCR and am looking to get it in .223 and possibly converting to 6.5 MPC.

    My concern regarding the cartridge is that I have read that it loses too much velocity with shorter barrels.

    I would like some feedback regarding actual chronographing that may confirm this and a comparison to other calibers, like 6.8 SPC for example.

    I love the feature of being able to change barrels quickly in the field with the XCR and would like to start off with a cartridge that will give good performance in shorter barrel lengths, if I decide to use them.
  2. Yunus

    Yunus New Member

    Stop by the introduction section and let us know a bit about yourself.

    I don't have any Chrono numbers but I'm sure they can be googled. I can say though that I have shot multiple AR-15's with 16" barrels, actually 14.5" with a flash suppressor and they are very accurate at up to 200 yards. I don't have much experience beyond 200 yards.

  3. planenut

    planenut New Member

    I think this is just handguns but maybe it will help...

    BBTI - Results
  4. robocop10mm

    robocop10mm Lifetime Supporting Member Lifetime Supporter

    Pretty much every rifle cartridge shoots faster in a longer barrel (with in reason). Going from a 20" down to a 12" barrel will give significantly less velocity. Small cartridges like the 5.56 rely on speed to give performance. Shorter barrels mean less speed. Larger diameter bullets like the 6.5 SPC rely less on speed and more on mass. Every cartridge is a compromise between bullet weight, velocity, portability, and shootablility. A .50 BMG has high bullet weight, high velocity, terrible portabilty and shootablility. The .22 short has low buellet weight, low velocity, high portability and shootablility. Everything in between is a compromise.

    The 5.56 in its military configuration relies heavily on velocity for its wounding capability. Shorter barrels do not give the kind of results that longer barrels do. Since we are not military members (for the most part) bound to international law, we can use expanding or frangible bullets that rely less on velocity because the bullet will expand and do the work for us.

    IMHO, there is nothing wrong with a .223/5.56 for defensive purposes as the range of bullet weights and construction allows for one to tailor the ammo to the mission.

    The 6.8 SPC is heavier, slower, similar in portability and shootability. One deciding factor may be ammunition cost and availability.