A rotary trimmer for trimming flash and the blow dome from a plastic bottle forming a portion of a plastic blow molded log discharged from a blow mold includes flash punching, a neck support plate, and a guillotine blade. The neck support plate is movable by a plate drive to move adjacent the neck of the plastic log to support the neck during cutting of the blow dome and cooperates with a log holder to essentially support the entire outer periphery of the neck. The guillotine blade is movable by a blade drive to pass through the plastic log and sever the blow dome from the neck of the log.