Aardvark......I've spent the last month or so refinishing a Marlin stock with Birchwood Casey Tru-oil.......I'm using an air brush, and have a very Glossy finish..........Still got a few coats to go before I'm done, but it's just about there!
I think you can get Tru-oil in a spray can......have you tried that?
I haven't tried polyurethene, but read somewhere that you can spray oil based over Tru-oil.........That would surly give a gloss finish........