Waterlox is a polyurethane and finishes very well.  I started with Pilkington's Poly finish in Alaska but it didn't give me the water resistance/proofing I needed in Alaska.  I talked to Pilkington and he said that Waterlox would work with his poly.  So I started using Waterlox for the first two or three applications and then used Pilkington's Poly to finish the filling of the pores.  Sometimes I used just Waterlox to fill the pores.  I always used Pilkington's Finishing Oil to finish the finish, no matter what the base was.  

Phil Pilkington was a chemist for many years before becoming a gun builder full time.  He developed the formula for his finish so that it wouldn't dry too fast.  That is what is needed to wet sand a stock and not get a mess.  The original Waterlox also wet sands well.  

Some people use pure Tung Oil to finish a stock.  I never tried it myself.  Pilkington's Poly finish and Waterlox both have some Tung Oil as an ingredient.  Boiled Linseed oil is a bear to work with and Tung Oil has better water resistance.

Frank