Defence group Chemring says it is trading in line with expectations but that its long-serving Finance Director will step down by the end of July.The first three months of its accounting year (November to January) have seen revenues of £137m, compared to £136m at the same point in 2011.Chemring says "strong growth" was generated in its munitions and countermeasure businesses, offset by reductions in the counter-improvised explosive device (IED) and pyrotechnics divisions. The firm now has 72% of expected revenue for 2012 covered by firm orders.A search is underway to find a replacement for Paul Rayner who will step down no later than July 31st. Rayner has been with Chemring since 1994 and has been Finance Director since 1999.Shares in the company had dipped 0.9% by 08:11. Over the last 12 months the stock has fallen 34%.BS