Any level 3 vest will stop it, especially if it hits the trauma plate.
.50 AE has been around in handguns for almost a decade, this is nothing really new.
BTW Sirloin, the .357 Sig, found commonly in many Sig pistols, like those used by the FBI, Secret Service, and "apparently" the Air Marshal service (I know the SigArms instructor who teaches them, he taught a course at our school) will rip through any level 2 vest, which is typically what most cops use. .357 sig isn't an overly large bullet, but it's travelling at warp speed.