A self-flushing small volume prover apparatus, method and system for removing foreign materials. A piston can be configured with a valve arrangement located within a cylindrical object in order to permit fluid to pass through an annular passage when the piston travels from a downstream position to an upstream position. An inlet port and an outlet port can be located at the bottom of the cylindrical object. The outlet port can be welded at the bottom of the bore cylinder so that foreign material can flow directly out of the prover bore cylinder via the outlet port. The velocity of the piston can remove the collected foreign material from the bore cylinder via the outlet port, thus creating a self-flushing prover.