FMJ yaw and upset performance

[LR1955]

To match the long-range (up to 1,000m) performance of the 7.62 M80, in terms of retained energy and other metrics, with a smaller and less powerful cartridge requires a bullet with a better ballistic coefficient than the M80's. The 123 grain Lapua Scenar seems to do that job very well in the Grendel, so it's a matter of getting close to the BC of the Lapua with a mass-produced FMJ military bullet.

As far as 77 grain 5.56's are concerned, I have the strong impression that no calibre smaller than 6.5mm is likely to prove acceptable as a replacement for 7.62mm, in terms of penetration and terminal effectiveness. The Chinese tried to make a universal cartridge with their 5.8x42 (in light and heavy loads), but their army is hanging onto their 7.62x54R MGs.

Tony:

This one shouldn't be too hard to figure out. How much better does the 6.5mm bullet have to be before it shows a quantum improvement in exterior and terminal performance?

Start out with defining what that quantum improvement is and the rest will be easy to solve -- on paper.

What must the BC and velocity be to match in exterior terms and then multiply by about 50% before anything can be proven in real terms. When that is solved, then look at powder technology and finally bullet construction.

LR55