Military decoy flare and mine detection firm Chemring was the biggest faller after it said unexpected delays in customer orders means full-year revenues will be around 5% below the board's expectations, while operating profit will be shy of market projections. In contrast, struggling foods manufacturer Premier Foods jumped over 15%. The firm announced today that Ian Deste, group sales director, had upped his stake, perhaps providing a boost to investor confidence.The miners were in demand as copper, gold and silver prices rose higher, supported by a weak dollar. Talvivaara Mining, New World Resources and Allied Gold Mining were all registering decent gains.The retailers were out of favour with SuperGroup dropping 10%. Carpetright and Debenhams were also lower. Investors could still be mulling over the Nationwide consumer confidence index for the month of October which was released yesterday. The main sentiment index fell 9 points from the previous month's level to 36, its lowest level since May 2004. FTSE 250 - RisersPremier Foods (PFD) 5.21p +15.44%Ocado Group (OCDO) 88.15p +8.83%Mothercare (MTC) 134.30p +5.50%Talvivaara Mining Company (TALV) 205.60p +5.33%New World Resources A Shares (NWR) 447.80p +4.92%Allied Gold Mining (ALD) 172.90p +3.53%Amlin (AML) 315.40p +2.57%Unite Group (UTG) 164.80p +2.36%Bwin.party Digital Entertainment (BPTY) 137.10p +2.31%BBA Aviation (BBA) 172.80p +2.01%FTSE 250 - FallersChemring Group (CHG) 408.20p -15.66%Supergroup (SGP) 532.50p -9.90%AZ Electronic Materials SA (WI) (AZEM) 230.80p -5.41%Ashtead Group (AHT) 158.00p -4.01%Carpetright (CPR) 430.60p -3.67%Elementis (ELM) 135.40p -3.63%African Barrick Gold (ABG) 518.50p -3.62%Northgate (NTG) 229.90p -3.52%Morgan Crucible Co (MGCR) 253.70p -3.50%Victrex (VCT) 1,080.00p -3.49%NR