1:32 can be a big problem. Try Model Dockyard (
www.model-dockyard.com to download their catalogue. They advertise a 1:32 Mk 9 40mm Bofors under TMD fittings pt no.SD707 but at £31.02 he may have to wait for Christmas. They also list weaponary under several other scales and generally have a big range of fittings.