6.5 or 6.8 out of a 5.56 case

[BoringGuy45]

I read about this concept in some magazines awhile ago, but it's since fallen by the wayside. While such a round would not have the ballistics of a 6.8 SPC or 6.5 Grendel, it seems like a sound concept. It would probably provide better terminal ballistics than a 5.56 (especially from a short barrel) up to the edges of normal combat range, but would still have a high enough BC to be effective at mid to longer range (400-500 yards).

I read about SSK's 6.5 MPC and it seems like a good idea. I also remember hearing about a conceptual round called the 6.86x40mm ARC, but I don't think it went anywhere. Any experience with this concept?

[BradL45]

Interesting round being worked on

Picture from the thread below

http://i53.photobucket.com/albums/g61/ron458/65001.jpg

6.5mm with a worked over 5.56 case, 100 Gr Ballistic tip going 2450 out of a 16 inch barrel..

http://www.ar15.com/forums/topic.html?b=3&f=121&t=518663

It should stack up , or be warmer than the MPC round

The 6x223(45) has more oomph than the 5.56, and Wilsons 7.62x40 has some oomph with the 125 Ballistic tip(maybe reach 2400-2500fps with handloads).

6.8 doesn't have the high BC bullets to really utilize the limited power contained within the 5.56 case. H from ARP was thinking about the 6.8x223 but I think it's on the back burner.

Once we see more of the coated(like the super performance) gun powders hit the shelf, I think we will see some good load work producing good numbers for the 6mm to 30cal in the 5.56 case. I think the 6.5 is around the sweet spot for bullet weight and velocity in the 5.56 case, 6mm a close 2nd.