Grendel as a Universal Infantry Cartridge

[woohoo]

A 130gr at 2550-2600fps with a long COL is totally doable with another bolt design, especially when you look at canister powders specifically for it. BjornF16 developed a load for his Savage 20" bolt-action Grendel with the 129gr Interbond on top of CFE, and was able to hit 2585fps before the velocities starting getting erratic. He used a longer COL of 2.350". If you went to 2.400" in a belt-fed, you could even get more case capacity.
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Do you know how long a 130gr 6.5 green bullet would be? If you want a 130gr green bullet you'll need to step up to a 7mm at least. I know some hate the green thing but the mil is going that way like it or not.
On top of the new green bullets all new cartridges will need to be designed for poly or lsat which is thicker than brass. The operating pressures should be kept down to 55k psi max in 110 degree temps. That is the spec that killed the 6.8s performance and reason Remington downloaded their ammo.
The cases used in MGs should have more taper than the Grendel which will also reduce the capacity.
We've been talking about bullet designs on Tonys forum for months. Mass production, terminal performance and BC must be considered. Also if too heavy they will not meet the weight reduction requirements, if to light they will not have the terminal performance. Using litz's perfect bullet design which with lead core bullets usually end up with a .675 BC, the optimum design is apx 5 calibers long. A 6.5 ends up in the area of 110-115gr when green. The 6.8 bullets range 118-123gr and the 7mms 125-130gr. All bullets regardless of caliber can have the same BC when using the same formula Litz uses. It seems to me the weapons the military are having produced have shorter barrels. The MK48s being reworked now have barrels shorter than 20" according to the company reworking them. All of that works against smaller cartridges. IMO Murray did the research and came up with the right idea for a LMG cartridge that will perform better than the 7.62x54 at range while giving close to the same terminal performance.