An American would've written instead, "To avoid the hassle of reloading frequently at the range, you may use high capacity magazines."
Tell me when you start your business and I'll be your first customer. Just do like the ice cream trucks and park in front of the gun range in a van. Clean the guns from your van. You don't have to have a FFL if you clean them while the customer is there with you (IANAL, lawyers may call me out if I'm wrong). Set up some stools, a TV, and serve them sandwiches while they wait to have their guns cleaned. Good luck!