Was passed down this watch for my 30th birthday and don't have any docs to see what model/ref this is. Any ideas other than opening the case back to see the serial?

 

Take it to a watchmaker and have take the back off. Omega puts all the information on the inside of the caseback.

 

No other option other than opening the watch..Maybe are peoples here which know which model it is but to be sure you will have to open it.

 

Agree with the above, you need to have it opened by a watchmaker.
My bet from this pic is that's a ref 2272 from the 40s.