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.

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.

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