Testing, testing...

[Tony Williams]

Shifting focus to the 7.62 makes a difference, with the Grendel representing the minimum caliber and case volume that should be considered.

I agree, on both counts. I would say that the old British 7x43 represents the top end (or its modern equivalent, Cris's 7x46 UIAC).

I am very sure 6.5 will be the optimal choice both in the analytic and test world. A reasonable study, however, would consider .25 caliber, 6.5, 6.8, and 7mm.

I am very sure that gelatin-based tests will show little or no practical difference between optimized bullets in these calibers and be close enough to that of the 7.62 M80 to count.

The M855A1 propaganda suggests that properly designed bullets in these calibers are also likely make choosing between the calibers difficult

How much a caliber improves the soldier's ability to hit in this family of cartridges will likely be the deciding factor. This favors the smaller calibers because

• Bullets of equal sectional density have slightly higher muzzle velocity in the smaller calibers for the same case volume
  
• Bullets of equal sectional density can get slightly better ballistic coefficients in the smaller calibers.
  
• Bullets of equal sectional density are lighter in the smaller calibers, reducing recoil.
  

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