05-25-2013, 02:51 PM
5.56, 6.8. 270AR. 6.5x47, Creedmoor, 308.
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I agree with others including Murry that a true mid sized cartridge could do it all. 1 cartridge for CQB, sniping and work in a LMG. Murry's 7mmUIAC is a great case size but I think a 6.5 or .277 projectile would perform better as an all around cartridge. It's very close to the 6.5x47 but the diameter of the Grendel. At 2.5" OAL it would require a new platform or a AR10 sized lower allowing for the longer carrier travel and smoother recoil impulse.
I like others believe if a cartridge the diameter of the Grendel is used in a combat rifle the bolt head would need to be larger for reliability. Murry's bolt was designed for a LMG so it's larger than what would really be needed for a combat rifle.
Photo shows a typical AR15 bolt beside Murry's bolt. Material was a soft test alloy to test the tool path, that's why it looks gummy. Next photo is AR15 bolts and my 800 series bolts(.441 and .473) which are plenty strong enough to handle the BRXs I've been shooting and the smaller .441 diameter cartridges
In 2010 I built 28 "AR12s" for lack of a better term. They were built on DPMS LR lowers with a down sized upper to cut the weight. Changing AR10 barrel profiles to AR15 barrel profiles removes much weight then the carrier loses another 4oz. Most were 308s but a few were built in 6.5x47. 308 or full sized ammo is still heavier than it needs to be. New powder designs are better than the old so we really don't need a case the size of the 308 now, the 6.5x47 proved that. A 7lb combat rifle with a decent barrel profile(not lightweight) is possible. No one in combat likes excess weight. Developing a new platform including mags and brass would be very expensive for a small business.
Will the NATO countries change? I doubt it but it would be nice to see.
[ATTACH=CONFIG]3341[/ATTACH]
I agree with others including Murry that a true mid sized cartridge could do it all. 1 cartridge for CQB, sniping and work in a LMG. Murry's 7mmUIAC is a great case size but I think a 6.5 or .277 projectile would perform better as an all around cartridge. It's very close to the 6.5x47 but the diameter of the Grendel. At 2.5" OAL it would require a new platform or a AR10 sized lower allowing for the longer carrier travel and smoother recoil impulse.
I like others believe if a cartridge the diameter of the Grendel is used in a combat rifle the bolt head would need to be larger for reliability. Murry's bolt was designed for a LMG so it's larger than what would really be needed for a combat rifle.
Photo shows a typical AR15 bolt beside Murry's bolt. Material was a soft test alloy to test the tool path, that's why it looks gummy. Next photo is AR15 bolts and my 800 series bolts(.441 and .473) which are plenty strong enough to handle the BRXs I've been shooting and the smaller .441 diameter cartridges
In 2010 I built 28 "AR12s" for lack of a better term. They were built on DPMS LR lowers with a down sized upper to cut the weight. Changing AR10 barrel profiles to AR15 barrel profiles removes much weight then the carrier loses another 4oz. Most were 308s but a few were built in 6.5x47. 308 or full sized ammo is still heavier than it needs to be. New powder designs are better than the old so we really don't need a case the size of the 308 now, the 6.5x47 proved that. A 7lb combat rifle with a decent barrel profile(not lightweight) is possible. No one in combat likes excess weight. Developing a new platform including mags and brass would be very expensive for a small business.
Will the NATO countries change? I doubt it but it would be nice to see.