Actually we normally refer to them as "Open Tip, Match" bullets, "OTM", but they are the same as the Boat Tail Hollow Point "BTHP" as made by Sierra (Nosler was involved with the Mk262 Mod0 lots, but Sierra is a sole supplier now as far as I know).
But no matter what we call them, the point is that the bullets were not designed to cause unnecessary suffering/wounding.
However if you take that same bullet, and chuck it into a mini-lathe to open up the open tip with a small drill, then you have a "law of land warfare" violation.
After all, our job is to kill the enemy as humanely as possible within the rules of engagement. But then again, when the enemy is not a uniformed military of a recognized combatant nation, the use of expanding ammunition by military personnel conducting "police or stability actions" was approved through the SOCOM channels.
So it would be totally legal to shoot a terrorist with a Winchester Ranger hollowpoint through your M9 when deployed in a FID role, but completely illegal to shoot that same guy with a hollowpoint if he happened to wear a uniform and you were deployed in a "war" role. Then to CYA you would use FMJ.
There is no human activity that cannot be made more complicated by getting lawyers and politicians involved.
Machine guns are awesome until you have to carry one.