Testing, testing...

[JASmith]

...All true, but the need to plough through barriers and to maximise the wound channel for non-critical hits argue for the bigger calibres.

I see convergence in the discussions.

Regarding the bigger calibres, there is no question that the bigger calibers with similar bullet shapes will perform better against barriers and generate bigger wound channels.

The difference is that we are striving to define a cartridge that can replace the 7.62X51 M80 round while reducing weight and recoil. In this model, we don't need the best performing round, just the one that slightly beats the M80 in all categories save for the one or two that really count.

So, while I can't yet claim to know the optimum caliber/cartridge combination, the stretched Grendel (similar to the Czech-based designs you've been looking at) seems like an excellent starting point.

Remember that the longer range engagements will tend to be dominated by weapons other than rifles. My view is that, in spite of my own fantasies of long-range marksmanship, the purpose of the rifle in to 600 to 1200 meter range is as much to keep the adversary honest while bigger weapons are brought to bear.

Fortunately, the 50+ year-old design of the M80 gives us a fair bit of wiggle room. This means that we have an opportunity to reduce weight and recoil while improving hit probability and numbers of rounds in the magazine and still be able to demonstrate at least M80 equivalence given a hit.