Access stores the binary object as OLE-Object with header and footer informations, and some decoding.
The best way, i found:
Change the original file source before upload (insert at the beginning of the source: ">>>", append after the source "<<<" ). Then upload with a default name (upload.bin). The filename can be stored in the database as text-field. In this case the database has no idea, wich type it is. It makes the default header-footer codes, doesnt change the original code, and saves the OLE Object as "Package".
By download cut the source from ">>>" to "<<<". And you have the original file.
(You have to know, that access database needs 10-30% more place on your hardisc as the original files)