Install new master cylinder without bleeding?

used to chuck it up in the bench vise and use a screwdriver to push the piston in and out with brake line stubs looped up and into the soup. fill to full and start pumping slowly, it may percolate up so dont put your face down there. keep back filling and pumping until the flow runs bubble free. then you can carefully remove the fittings and attach your old ones. Gently push on pedal a few times and the top bubble should work its way out the MC. Youll know when you got the hard pedal. Todays MC's have plastic plugs supplied that somehow 'do' this.....? DOT-5 doesn't eat paint but may not be 100% compatible with OLD brake seals.