Home Depot has some metric size screws, but I would not count on finding one that is the right size for that use. Gun Parts Corp shows the grip screws for the BM but indicates "out of stock".
I have not checked on the dimensions, but it might be possible to drill and tap that Star to use M1911 grip screws. If so, just do all four holes so they are the same; Brownells has the tap.
Jim