Scottish soft drinks firm AG Barr remains on track for a first half sales rise despite being hit by disappointing weather in the four weeks to 9 July.The maker of Irn-Bru, Tizer and a host of other drinks said sales for the six months to 30 July are expected to be up by about 3.5% from the same period the previous year at £123m.Barr, which has been selling cans of Irn-Bru at a discounted price of 49p since before the start of the year, said it has continued to grow volumes without launching promotions to the same extent as competitors.Barr also said it had experienced "short-term capacity issues" due to delays in manufacturing investment at its plant in Cumbernauld."Final installation activities are expected to be completed in the next few weeks and we anticipate a gradual improvement in our production capacity and efficiencies over the coming months," the company said.The company said it looks "forward to the second half with cautious optimism and the full year remains on track to meet our expectations."At 0915am, shares in Barr were down by 2% at 1,275p.---RG