WASHINGTON (MarketWatch) - Orders for big-ticket U.S. goods sank 7.3% in July, mostly because of a large decline in contracts for jetliners and large military goods, the government said Monday. Economists surveyed by MarketWatch had expected orders to drop 4.9%. Stripping out the volatile transportation sector, orders fell a much smaller 0.6%, the Commerce Department said. Orders for core capital goods, a key barometer of private-sector business investment, slipped 3.3% to mark the first decline in five months. Shipments of core capital goods, a category used to calculate quarterly economic growth, dipped 1.5% in July. Orders for June, meanwhile, were unchanged at a 3.9% increase. In 2013, orders for durable goods have risen a modest 3.3% in the first seven months of the year compared to the same period one year earlier. Core orders are up 3.8% in the same span