I think Brian’s 99% pretty much confirms it then.
Anyone needing 5BA screws might do worse than seek out a model engineering supplier as 5BA is a size still used in the hobby. (1.5″/ft being a popular scale and 5BA scales to a 1″ bolt — not a lot of of people know that!) The only problem here is that you might only be offered them with a hexagon head and quite possibly with a smaller 6BA head on it at that. (It’s a scale thing.)