I believe Wisconsin Cartridge loads for it but I don't know if they have any in stock. you might try Reed's ammo, Midsouthshooterssupply, Natchezss, MidwayUSA, Graf and Sons, Wideners.
If you can receive a shipment by FedEx from an individual, I believe I know where a few boxes are of Winchester 375. It might be kinda high priced.
If you can receive a shipment by FedEx from an individual, I believe I know where a few boxes are of Winchester 375. It might be kinda high priced.