Mumbai, April 30 -- COMEX Copper futures tumbled on the last session of April, shedding nearly 5% and giving up bulk of the recent gains as weak Chinese manufacturing sector weighed on sentiments. China's manufacturing purchasing managers' index fell to a 16-month low in April as the impact of tariffs started hitting producers. China's official April manufacturing PMI fell to 49.0 from 50.5, sliding in contraction territory. COMEX Copper has tanked following this, testing around one and half week low and currently quoting at $4.64 per pound, down around 4.87% on the day. The metal has lost nearly 8% this month. MCX Copper pared around 3% to trade at Rs 830 per kg. Meanwhile, in Asia, China's Shanghai Composite index closed down 0.23%. Hong ...