Here is a snipit from last months Shooting Times;
The larger barrel extension required a larger upper receiver to accept it. The engineers started with a raw R-25 extrusion of 6066-T6 aluminum. The internal dimensions were machined to match that of the R-15. Externally, the receiver was machined to include a standard forward assist, a brass deflector, and a Picatinny-spec flattop rail. With a width of 1.3 inches, the receiver body is 0.1 inch wider than the standard R-15. A recess is milled in the left side of the receiver to accommodate the upper paddle of the lower's bolt release. To allow room for the larger .30 RAR spent cases, the ejection port is 0.58 inch, compared to the 0.50 opening of the standard R-15.
You can read the entire article here;
http://www.shootingtimes.com/longgun_reviews/ST_r15andthe30rar_200905-A.jpgI do think that it is great that a big time gun manufacturer put the R&D into a project like this, it will help out the whole AR industry in the long run. I just wish they would have spent a little time finding out what the general shooting populace would like to see chambered in the AR15 platform.
I'm affraid this will become another 6mm Remington, SAUM, 260 Remington, 280 Remington etc... all great ideas, just wrong timing, wrong twist, wrong rifle or wrong caliber.
Time will tell
