6.8x45mm Kramer “Urban Combat Cartridge”

The 6.8x45mm is an alternative to the 6.8 SPC cartridge that has been getting a lot of attentio. Developed by Larry Kramer of Kramer Defense (They have no website that I could find). The parent cartridge is the .223 Remington / 5.56mm NATO.

Its advantage over the 6.8 SPC is that a standard AR15 bolt face and magazine can be used, and that the case can be formed from .223 brass instead of the obscure .30 Remington.

Kramer 6.8 1
5.56mm vs. 6.8x45mm.
Photo from Defense Review.

The 6.8 SPC can send a 115 gr bullet at 2625 ft/s while the 6.8x45mm Kramer can push the bullet to 2500 ft/s. Kramer claims that once the round is refined it will be able to achieve 2600 ft/s from a 16″ barrel.

A lot of development has gone into the SPC by Special Forces members and Remington. I think it is likely that they would have tried the .223 case as it would be a logical choice for the next AR/M16 cartridge. I know very little about wildcats and cartridge development but I would guess there was a good reason they went with the .30 Rem as a parent instead of the .223 Rem.

More at Defense Review

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Daverino

    I think what we need to do is have a competition to see what the best battle cartridge is with today’s technology. If we do it for planes ships and soldiers, something similar could surely be put together for such a vital part of our national defense. I do not think they would be interested, but perhaps Consumer Reports (the magazine) could do it, the hardest part would be coming up with the criteria.

  • I think the problem is that with most cartridges there is always a trade off. fast vs. slow, large caliber vs. small caliber, heavy vs. light, hollow point vs. solid vs. amour piercing. Then when you throw preconceived ideas into the mix it becomes very hard to choose a cartridge.

    If the “powers that be” were not convinced that any cartridge less than .30 in caliber was useless we would all be using a 7mm already. http://en.wikipedia.org/wiki/.280_British:

    “Ironically, in 2002 the Americans developed a new military calibre called the 6.8 mm Remington SPC which is ballistically very similar to the .280 British cartridge. Over 60 years after the .280 British cartridge was designed, the clock has now turned full circle.”

    What needs to be developed it not a new cartridge but a specification of what is needed for the troops on the ground. This is were R&D needs to happen. Once a specification is developed, then developing or choosing a cartridge will be much less subjective.

  • There is an old saying in racing circles: “There is no replacement for displacement.” It applies to cartridge wildcatting as well.

    The only way you can get equal or near equal performance to a larger volume cartridge case from a smaller volume cartridge case is to raise pressure. Raising pressure has its limits. And just because a wildcat cartridge seems safe in its inventor’s limited testing, that still doesn’t make it acceptable for all situtations. For instance, while a cartridge might be within safe pressure limits at low or moderate temperatures, higher temperatures can raise pressures to unacceptable levels.

  • Hmmm. I quite like that idea. And even LESS expensive to convert the current inventory to a more effective cartridge.

  • Good information about this 6.8 at 68forums.com—explains some of the advantages, disadvantages and how modern powders allow for increased velocities while working within the limits of materials and pressures.