'68 Coronet, Reproduction tandem booster & large bore (1.125) factory style reproduction master cylinder. SSBC front disk conversion.

When bench bleeding the MC, the piston retracts easily, but stops around .400" short. Over the course of 45 seconds it slowly retracts to its final position with the end of the piston protruding .090" past the flange.

Isn't it supposed to easily retract all the way without a hang-up? This style of MC has a screw from the underside that holds the rear piston in place, as opposed to having a c-clip as the positive stop at the end of the bore.