Chemring, the military decoy flares and mine detection firm, saw shares rise after it said its US subsidiary, Non-Intrusive Inspection Technology (NITEK), won a $38.4m contract from the US Army. The contract is for the supply and initial spares of 64 Husky Mine Detection Systems for high reliability clearance of buried mines in support of US peacekeeping operations around the world. Deliveries under the contract will be made over the period to October 2011. easyJet was among the risers Tuesday afternoon after the no frills airline said it would exercise its option to take delivery of 15 Airbus A320 aircraft between 2012 and 2014.The company has agreed new options over a further 33 A320 aircraft, while 20 of the A319 aircraft which easyJet had contracted to acquire from Airbus have been converted into orders for A320 aircraft. easyJet has the right to exercise the additional 33 options up to March 2013. Premier Oil shares were boosted after an oil discovery at the Varadero exploration well in UK Central North Sea block 28/9, where the company has a 35% interest. Initial analysis indicates the discovery of a 400 feet hydrocarbon bearing interval with a calculated net pay of 106 feet.FTSE 250 - RisersOcado Group (OCDO) 196.70p +10.32%Kenmare Resources (KMR) 35.05p +7.19%Exillon Energy (EXI) 350.00p +6.71%ITV (ITV) 73.95p +5.57%Berkeley Group Holdings (BKG) 937.50p +5.34%Barratt Developments (BDEV) 93.05p +4.96%Morgan Crucible Co (MGCR) 255.40p +4.84%Cable & Wireless Worldwide (CW.) 68.75p +4.64%Renishaw (RSW) 1,286.00p +4.55%Pace (PIC) 191.00p +4.54%FTSE 250 - FallersDomino Printing Sciences (DNO) 623.00p -4.15%Gartmore Group Ltd. (GRT) 88.60p -3.70%AZ Electronic Materials SA (WI) (AZEM) 299.20p -3.48%Croda International (CRDA) 1,566.00p -3.09%Misys (MSY) 334.10p -2.59%Marston's (MARS) 111.80p -2.36%Moneysupermarket.com Group (MONY) 76.35p -2.12%Fidessa Group (FDSA) 1,518.00p -2.06%Avis Europe (AVE) 232.20p -2.03%Sportingbet (SBT) 60.50p -1.94%