In this apparatus rotatable, annular guide fittings receive the bar stock at support standards which are spaced apart in succession along the path of the bar stock at the inlet side of a screw machine. Each fitting contains spring-biased rollers which guide the bar stock between them and yieldably restrain it against vibrating transversely. The bar stock is unconfined except in the spaced-apart fittings. For a multiple screw machine, each support standard has a rotatively indexed cross plate carrying several such fittings, one for each bar stock.