Yes, they're legal, but in practice they're probably worse at their job than regular hollow points, wad cutters or ball ammo. The problem is that those petals are designed to break off early, and only produce a narrow 2-4" wound channel akin to a bb or rat shot, not very deep on the average, let alone fat adult. Meanwhile, you're left with the small base of the bullet remaining to do the damage.
With a regular hollow point, you get deep penetration and a tremendous amount of expansion, plus the occasional extra wound tracts caused by some broken petals, etc....
Here are some examples -
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Also the way they're designed to break off into long, narrow shards also presents problems against hard and semi hard barriers like wood, glass, etc.... You wind up loosing most of petals going through them.
