06-14-2013, 07:25 AM
A more in-depth search of the 6.5 Grendel Forum Archives netted a rather extensive Discussion, as to why the 50,000 psi limit was established for the strong 6.5 Grendel cartridge case, when used in the standard AR-15 platform, [B]Is anyone currently selling a 60K psi bolt? (http://www.65grendel.com/forum/archive/i...-3549.html).
And, from an upbeat Discussion on the .30 RAR necked down to 6-7mm, on another Forum, ". . . I think the RAR could be a family of cartridges in the [R-15] that would serve target shooters and hunters alike, who are looking for longer-range or heavier pill performance, in addition to varminters. There is no need to do all the High Pressure Testing and MPI on the AR10 bolt because it has so much mass, and was designed around the cartridge it was meant for, namely the 7.62x51 NATO. The AR15 bolt, receiver set, and extension was NOT designed around the 5.56 NATO, but the 50,000 psi limited .222 Remington. They never changed the geometry of the stress components when they blew the shoulder forward and ramped up pressures to well over 50,000 psi for the .222 Remington Special, since the dimensions would have grown maybe .100", so they just left it as is, but then started realizing the need for Carpenter 158 versus 8620 on the bolt, and the whole HPT/MPI process to QC the bolts. I like that the RAR uses an AR10 bolt lug & face geometry, with an AR15 bolt body, enlarged outer diameter just behind the lugs to support them, and a larger extension to handle the hoop stress. . . ."
All of which begs the question, What if Remington necked-down their .30 RAR to 6.5mm? The approx. 44 grain (water) capacity of the cartridge is within 4 grains of the superb 6.5x47mm Lapua, which requires an AR10-length action.
Oh, the painfully slow evolution of American sporting arms and ammunition! [/B]
And, from an upbeat Discussion on the .30 RAR necked down to 6-7mm, on another Forum, ". . . I think the RAR could be a family of cartridges in the [R-15] that would serve target shooters and hunters alike, who are looking for longer-range or heavier pill performance, in addition to varminters. There is no need to do all the High Pressure Testing and MPI on the AR10 bolt because it has so much mass, and was designed around the cartridge it was meant for, namely the 7.62x51 NATO. The AR15 bolt, receiver set, and extension was NOT designed around the 5.56 NATO, but the 50,000 psi limited .222 Remington. They never changed the geometry of the stress components when they blew the shoulder forward and ramped up pressures to well over 50,000 psi for the .222 Remington Special, since the dimensions would have grown maybe .100", so they just left it as is, but then started realizing the need for Carpenter 158 versus 8620 on the bolt, and the whole HPT/MPI process to QC the bolts. I like that the RAR uses an AR10 bolt lug & face geometry, with an AR15 bolt body, enlarged outer diameter just behind the lugs to support them, and a larger extension to handle the hoop stress. . . ."
All of which begs the question, What if Remington necked-down their .30 RAR to 6.5mm? The approx. 44 grain (water) capacity of the cartridge is within 4 grains of the superb 6.5x47mm Lapua, which requires an AR10-length action.
Oh, the painfully slow evolution of American sporting arms and ammunition! [/B]