Defence group Chemring surged after saying that expectations for the financial year ended October 31st remain in line with previous guidance despite the adverse market backdrop.Pork producer Cranswick also gained after beating forecasts with its interim results as first-half pre-tax profits rose 16% to £26.1m.Thomas Cook Group climbed on the news it has agreed to sell its specialist activity tour operator Neilson Active Holidays to private equity firm Risk Capital Partners for £9.15m.Meanwhile, power plant operating and oil group Essar Energy sank after seeing first-half core profits fall 7% to $543.7m due to a weak Indian rupee.Gold producers Centamin, Hochschild Mining and African Barrick Gold were in the red with the price of the precious metal trading near a four-month low as the demand of safe-haven assets reduced.FTSE 250 - RisersChemring Group (CHG) 214.50p +10.34%IP Group (IPO) 171.00p +8.09%Cranswick (CWK) 1,165.00p +5.91%RPS Group (RPS) 293.60p +4.19%Oxford Instruments (OXIG) 1,467.00p +3.38%Worldwide Healthcare Trust (WWH) 1,230.00p +3.36%Carpetright (CPR) 605.00p +3.33%Supergroup (SGP) 1,149.00p +3.33%F&C Asset Management (FCAM) 96.55p +3.21%Dunelm Group (DNLM) 857.00p +3.00%FTSE 250 - FallersEssar Energy (ESSR) 89.15p -11.38%Centamin (DI) (CEY) 44.00p -7.00%African Barrick Gold (ABG) 165.20p -3.84%Moneysupermarket.com Group (MONY) 172.50p -2.82%Hochschild Mining (HOC) 126.20p -2.55%Taylor Wimpey (TW.) 110.10p -1.70%Kenmare Resources (KMR) 18.55p -1.59%Lonmin (LMI) 307.40p -1.54%Polymetal International (POLY) 516.00p -1.53%NMC Health (NMC) 391.30p -1.44%NR