From Guns.com:

Two former retailers of now-banned bump stock devices are suing the federal government for damages they incurred after having to destroy their inventory.
The plaintiffs include two companies, Minnesota’s Modern Sportsman and Texas-based RW Arms, as well as two individuals, Mark Maxwell and Michael Stewart, who in all lost 74,995 bump stocks to the ban which took effect late last month. The case, filed in a Washington, D.C. federal court, argues that the ban’s requirement that bump-stocks be surrendered or destroyed within a 90-day period, with no opportunity for registration, violated the Takings Clause of the Fifth Amendment which states that private property can’t be taken for public use without compensation.