Yes, they're legal.
I've never seen anyone stock them, but I've seen and purchased .308 ones on the EE a couple years ago.
The bullets are fairly long for their weight, so you may need a faster twist than you would for a FMJ of the same weight. Because of the increased bearing surface and increased friction, you may reach max pressure before max charge weight, but this is arguable. Just work up a load as normal, and make sure your backstop isn't flammable.