I have been using a 6.5 PPC in an AR15 for 2.5 years.  Using a 123 grain Lapua Scenar in a magazine length, velocity runs comfortably 2650 fps.  In early 2004, a factory 6.5 PPC AR15 will be available from Alexander Arms.  In addition, factory brass, loaded ammo and magazines designed for the PPC will be available as well.  The cartridge is being rebranded the ".26 Grendel".  

The 6.5 PPC was developed at the same time as the 22 PPC, 6 PPC, 7PPC and 30 PPC by Lou Palmisano and Ferris Pindell,,,the 2 "P's" in the PPC.  Since Palmisano and Pindell are benchrest shooters and for their use, the 22 PPC and 6 PPC went into use for benchrest.  In addition, Palmisano told me he uses the .30 PPC for deer hunting in his home state of PA.

As far as the 6.5x45,, it would work, but it would require bullets to be set back in the case to work magazine lenght reducing capacity and velocity.  Compared to the 6.5 PPC, you would loose velocity, but would gain use of standard magazines and cheaper brass.

As far as the "Whisper" rounds, I have had and a friend now owns a .30 "Whisper".  The "Whisper" series of rounds works well as a subsonic round which it was designed for.   In higher velocity rounds, it doesnt do anything special.  My friend acquired the .30 "Whisper" to use for feral hogs, but switched to the .50 Beuwolf.

If you didnt want to go the PPC route, I would go with a 6x45 or 6.5x45 to be able to use standard .223 brass.

The 6x45 actually was the benchrest round before the PPC came into dominance.  Getting reamers and dies is not really a problem.  I am sure Redding has a few on the shelf ready to ship.

100 grain .224 bullets.....that would be an interesting concept, but the reality of it is that 80,90 or heavier .224 bullets are only applicable for single round loading,,,not magazine length rounds.

In the 6.5 PPC, I can shoot out of the magazine, bullets with a .540-.570 BC.  It does give an advantage in the rapids and transulates into one round, one load for 200, 300 and 600 yard courses of fire. This is the same methodology that David Tubb uses for the 6mmX in his Tubb 2000 rifle --- One round, one load,,,across the course.

The magazine modification I have had to do is fairly easy.  I just take a pair of needlenose pliers and massage the feed lips to raise the bullet tips in GI 20 round magazines about 1/8 inch.

The 6.5 PPC (.26 Grendel) will be commercially available and has been seen by the US DOD.  Why would the US DOD be interested?  It is a known fact that the .223 Rem has shown its shortcomings in Desert Storm and Afghanistan.  90 grain JLK bullets are a single round match solution, but do nothing for military application. The 6.5 PPC with a 123 grain at 2650 fps exceeds the ballistic performance of the .308 "sniper" rounds and does it maintaining supersonic performance at 1000 yards with less recoil.  Test loads are showing 2 fps velocity spreads and I have consistently run loads with single digit velocity spreads.

To maintain 30 round magazine loads,,, you will have to stay with the 6x45.  

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