[MHGinTN]

No need for that, just go the route of the AK74 projectile, with hollow cavity in front of a solid portion and boattailed, pushed at close to 3000 ft/sec

[Redcitizen]

Wasn’t the AK round a bit slower than 3000 fps?

[papertyger]

No need for that, just go the route of the AK74 projectile, with hollow cavity in front of a solid portion and boattailed, pushed at close to 3000 ft/sec

Agreed. Just because a bullet has a hollow point doesn't mean it has to expand. However, the hollow point does cause the bullet to tumble more reliably than just the hinky geometry of the standard 5.56 round.

That's why the 28 grain 5.7x28 round incorporates the feature. The hollow point will collapse somewhere along the perimeter of the cavity and initiate the tumble in as little as two inches of penetration. Furthermore, because the tumble starts somewhat quickly after the initial penetration, it tends to dump ALL the energy Very quickly, but at a greater depth than the standard round.