6mmAR Turbo: Ultimate AR15 Cartridge?
Robert Whitley has developed the very accurate “6mmAR” cartridge based on Lapua 6.5 Grendel brass necked down to 6mm. This round is optimized for the AR15 platform, and provides excellent performance with 105-108gr bullets, with ballistics that beat both the .223 Rem and the 6.5 Grendel.
Not content with the success of the plain 6mmAR, Robert has created a new wildcat, the “6mmAR Turbo”. By moving the shoulder forward (while retaining its 30° angle), Robert has designed a case that delivers more velocity: 2850-2900 fps with 105-grainers.
In driving the 105s to 2900 fps, the Turbo rivals the performance of the larger 6mmBR cartridge, in a round better suited for the AR platform, with less bolt thrust and better feeding from the magazine.
Jerry Tierney (2008 NBRSA 600-yard Champion) recently started testing his own Whitley-built 6mmAR Turbo upper. He tells us: “This round is impressive. I am getting 6BR velocities with Berger 105s — no question. And the accuracy is there. Case forming is easy. Since you start with the 6.5 Grendel you just neck down with a die set short, and you have a false shoulder that provides a perfect ‘crush fit’ in the chamber. Bottom line it works. Really well. This thing gives the AR15 long-range bolt-gun performance. I hope the military is paying attention.”
Whitley explains: “The Turbo definitely has a good bit more speed than the 6mmAR. For a guy wanting to shoot plain bullets out of an AR-15, it appears somewhere between 2850-2900 fps for a bullets like the Berger 105 VLD is a realistic number. With moly bullets, probably a bit more is possible. For the chrono work, all bullets were plain (no moly) and I pushed it to see where was a realistic upper end. I think about 2900 fps with naked 105 Bergers is a ‘practical max’.”
