spat
.700 Nitro Express
Or just sell it to criminals.To not get caught they'd have to sell it all loose rounds. All that ammo can be tracked by lot numbers, date of manufacture etc. There may be a huge influx of ammo cans and boxes of loose ammo online along with projectiles and primed brass.
If your customers got their guns illegally, they probably DGAF where the ammo came from.
Maybe they'll use it as a promotional incentive ? "Buy a lightly used 9mm with the serial number ground off, get 200rds of ammo free".