Compiled By Deborah Austin Manufacturing activity declined slightly in September, shows the APICS Business Outlook Index, which fell to 49.3 from August's 51.5. An overall index below 50 signifies lower-than-average growth. But APICS forecasts no hard landing for the economy: Current and future components, close to 50 in September, indicate average growth in coming quarters. The index, released monthly by APICS-The Educational Society for Resource Management, provides estimates of current and future manufacturing activity. Unfilled orders rose almost 1% in September, resulting from above-average gain in new orders and a decline in shipments. Manufacturing inventory stocks rose slightly, after August's slight decline. The Desired/Actual Inventory/Sales Ratio fell sharply to 38.8 from 56.7; a ratio below 50 means inventories are higher than wanted. Firms may show caution in rebuilding inventory stocks, says APICS.