Its not, civilians CANT own one. LEO/CLASS III dealers... can. It sucks.
Oh....I never really cared for having a FA anyways, cost to much ammo wise...If i was going to have a FA I would have one like my friend that has an original MG42 passed down through his family his grandfather was OSS in WW2 and brought it back, all original...It's legally registered but even he says having it is sometimes more trouble than its worth, it more of just a family heirloom than anything else..