.280 Enfield...Ahead of its time

[stanc]

My own view is that when LRRPF52 convinces the powers that be to adopt the Grendel for the LMG role, it will be in a mode where the pressures go to more like those allowed for the PPC and the overall cartridge length is relaxed to accommodate the longest bullets (e. g. 130 - 144 gr copper-steel) with the bullet so that there is no protrusion into the powder volume beyond that needed to get about a caliber of contact between the bullet shank and the case neck.

Since Paul wants to stick with 5.56 NATO for carbine and rifle, and use 6.5 Grendel only for (what I like to call) his Optimized Machine Gun (OMG ), there is no need for cartridge OAL to be constrained by M16 mag well dimensions.

That does allow the projectiles to be loaded long for minimum impact on powder volume, and together with higher chamber pressure, would enable a significant increase in muzzle velocity.

However, even if the target muzzle velocities be achieved in LMG barrel lengths (14.5"-18") currently used, and assuming the link issue can be resolved, one very important question remains:

Are 130-144gr "green" (steel/copper and steel/steel) and conventional steel-core ball bullets actually feasible? Nobody has yet presented any evidence that such military projectiles are viable.

The heaviest example I know of is the 6.5 Swedish AP, at 113gr, well under the specified weight range for the OMG concept.

The 130gr TSX cited by Paul is a 100% copper bullet with a flat base. Weight loss incurred by using lower density steel, and going to a boat tail shape (to maximize long range performance), would reduce projectile weight to circa 115gr, at best.

If anyone can prove me wrong, please do so.