Need to work out what the threading is on the BB.

If its a newer Oschner frame its most likely Italian. But some of these frames are Swiss and may have swiss BB. Other common type would be french and english.

If the BBs are too small sounds like you're trying English BBs in the frame.

See here for some details.
http://www.bikeforums.net/archive/index.php/t-71331

BTW if you bought this cheap of Ebay just recently (blue frame, 54cm < 100 USD) then you will need a Swiss BB. Either a pricey Edco unit or get Phil wood cups for a swiss BB and use the spindle from another BB.