Theoretical: The SOCOM M4A1 post-adoption of the FN AC

[funkychinaman]

So hollow points were specifically banned by Declaration II of the Hague Convention of 1899:

The Contracting Parties agree to abstain from the use of bullets which expand or flatten easily in the human body, such as bullets with a hard envelope which does not entirely cover the core, or is pierced with incisions.

The present Declaration is only binding for the Contracting Powers in the case of a war between two or more of them.

It shall cease to be binding from the time when, in a war between the Contracting Parties, one of the belligerents is joined by a non-Contracting Power.

Interestingly, "the use of projectiles the object of which is the diffusion of asphyxiating or deleterious gases" was also banned at the same convention. (Declaration III.) This obviously didn't stick, but it could be the reason why the Germans initially only released chemical weapons from gas cylinders. It wasn't until later that both sides started filling projectiles with the stuff.