Kramer Defense Introduces New 6.8x45mm UCC Round

    Kramer Defense has released a new round for the AR-15 that they are calling the “6.8x45mm Urban Combat Cartridge”. The round is based on the 5.56mm case, necked up to .277″ caliber:

    Las Vegas, Nev. – -( After four years of research and development, Kramer Defense announced the commercial release of the 6.8x45mm Urban Combat Cartridge (UCC) as a cost-effective, ballistically superior upgrade for the AR-15, M16, and M4 platforms.

    The 6.8x45mm UCC provides military, law enforcement, and civilian users the ballistic performance similar to the 6.8mm Remington Special Purpose Cartridge in a package that is significantly more cost-effective and easily retrofitted to existing AR-15 patterned carbines.

    Based on the 5.56 NATO cartridge case, the 6.8x45mm UCC offers a significant ballistic advantage over its parent cartridge and even outperforms the 7.62x39mm and the popular .300 AAC Blackout cartridges, when fired from similar barrel lengths.

    The accompanying ballistics chart comparing these cartridges shows the advantage that the 6.8x45mm UCC provides the user.

    6.8x45mm Urban Combat Cartridge UCC Ballistics Chart
    6.8x45mm Urban Combat Cartridge UCC Ballistics Chart

    The result of the company’s development work is a cartridge that offers AR-15 users the ultimate in flexibility. The 6.8x45mm UCC has proven to be ballistcally superior in short-barreled AR-15 carbines, cycles flawlessly in selective-fire weapons, handles projectiles suitable for hunting applications, and has performed extremely well in initial sound suppression tests.

    “While we were focused on a solution for combat, the end result is probably the most efficient cartridge you can put in an AR-15,” said Larry Kramer, president of Kramer Defense.

    “The 6.8x45mm UCC offers the best trade-off balance of increased terminal performance, cartridge size, projectile weight, velocity, weapon compatibility, magazine capacity and controllable recoil. It really is the ultimate intermediate caliber.”

    Kramer Defense has loaded ammunition and complete AR-15 upper receivers for the 6.8x45mm UCC in stock and ready to ship.

    6.8x45mm Urban Combat Cartridge UCC
    6.8x45mm Urban Combat Cartridge UCC


    Kramer Defense currently offers two commercial loadings for the 6.8x45mm UCC:

    • Standard Ammunition with 115 grain Nosler Open Tip Match (OTM) at 2,500 feet per second
    • Premium Ammunition with 110 grain Hornady Open Tip Match (OTM) at 2,500 feet per second 


      AR-15 Upper Receivers

      • Complete upper receivers available through Kramer Defense feature:
      • High pressure tested and magnetic particle inspected bolt
      • Premium Lothar Walther barrels made of LW19 chrome moly steel that are polygonally rifled, chromed lined and have a twist rate of 1:11.3

    Longtime readers of my writing will know that I am skeptical of the utility of the new round. I’ve examined similar rounds to the new Kramer Defense offering previously. In 2014, I wrote a post where I designed a round similar to the 6.8×45 UCC to illustrate the numerous disadvantages that come from necking up the 5.56mm case, and earlier this year I wrote a post examining the surprisingly poor ballistics of the 6.8mm SPC, which is the ballistic superior of the new 6.8mm round.

    For the new round, my skepticism extends to the chosen case length as well; the round appears to either be incompatible or to be poorly compatible with existing 6.8mm SPC projectiles, as its case is longer by approximately 2.2mm. Further, the ballistic chart published by Kramer does not appear to reflect actual ballistics in standard conditions. The stated retained energy of the 5.56x45mm round at 500m is, according to the chart, about 400 ft-lbs (542 J). This is an accurate figure for M855 when fired at 9,000 ft altitude, but is about 36% higher than the correct figure for sea level. The figures for the 6.8×45 and the other two rounds are likewise inflated. Another possibility is that the Kramer chart is mis-labeled; if the chart tracks energy in Joules and not ft-lbs, the figures used would be approximately accurate.

    The round could prove useful for hunters living in states where calibers below .243″ are not allowed, if a sufficient supply of upper receivers and ammunition is made available, however.

    Nathaniel F

    Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. He can be reached via email at [email protected]