Grendel as a Universal Infantry Cartridge

[Variable]

I share your disappointment, but in hindsight the result should perhaps have been expected.

In the video I posted, 7.62x39 lead-core 123gr FMJ @ ~2300 fps failed.

The 6.5 Grendel lead-core 100gr FMJ @ ~2200 fps (10.5") and ~2400 fps (14.5") has less energy and momentum than 7.62x39.

7.62 NATO 147gr FMJ punches through both sides of a block, with sufficient residual velocity to inflict serious, if not fatal, wounding.

Your demo gives cause to doubt that 6.5 Grendel is capable of replacing 7.62 NATO.

Unless a much better projectile can be developed, and launched at much higher velocity...

Yeah. I hate to reload, but maybe a 120gr. Norma FMJ? I know it's not anywhere near "green" though.