Enhancing production of resin withing specifications

This invention relates to optimizing properties of polymeric resins, particularly polyolefins, made in continuous production runs, including transitions from the manufacture of one polymer product to another. It includes methods and apparatus for utilizing maximum amounts of products having properties which vary within and/or outside a set of specifications. A set of trim forward bins is utilized to set aside, distribute and allocate portions of granular product made in a continuous, usually fluidized bed, olefin polymerization reactor, to form blends which more efficiently utilize the products made during transitions from one set of specifications to another and/or to maintain a target property substantially continuously during steady state production of a single product.