NEW YORK (AP) â¿¿ Moody's Investors Service on Tuesday raised its senior unsecured rating for Precision Castparts Corp. to "A2" from "A3," citing the metal parts maker's strong profitability and free cash flow generation, limited debt and favorable prospects. The ratings service also boosted the Portland, Ore.-based company's short-term rating to "Prime-1" from "Prime-2." The outlook on both ratings is stable. Moody's noted that Precision Castparts has closed on 13 acquisitions totaling more than $2.5 billion over the past 18 months. While it assumed some debt, most of the needed financing came from the company's internal sources. The ratings service added that it expects the company's volumes to expand in fiscal 2013 and beyond, as production of certain kinds of aircraft increases. Shares of Precision Castparts rose 12 cents to $159.21 in afternoon trading.