U.S. BANK DISCOUNT BORROWINGS 228 MLN DLRS U.S. bank discount window borrowings less extended credits averaged 228 mln dlrs in the week to Wednesday March 18, the Federal Reserve said. Total borrowings in the week rose 83 mln dlrs to 502 mln dlrs, with extended credits up three mln dlrs at 274 mln dlrs. The week was the first half of a two-week statement period. Net borrowing in the prior week averaged 148 mln dlrs. Commenting on the two-week statement period that ended on March 11, the Fed estimated that banks had daily average net free reserves of 759 mln dlrs rather than the 660 mln dlrs first reported. A Fed spokesman told a press briefing that there were no large single day net misses in the Fed's reserve projections in the first week of the latest bank statement period. None of the 14 large money center banks borrowed from the discount window during the week and all of the Wednesday borrowing was made by the smallest banks. For the week as a whole, the borrowing was split roughly evenly between the large regionals and the small banks. Natural float ranged from a low of near zero on Thursday -- for which the Fed spokesman could give no particular reason -- to a high of nearly 750 mln dlrs on Tuesday. The Tuesday peak included about 100 mln dlrs of transportation float in mid- and south-Atlantic states. Noting that the weather was "basically good" for March, the spokesman said that transportation float averaged under 500 mln dlrs a day for the full week. Float related as-ofs were a negative 400 mln dlrs on Wenesday due to a number of unrelated cash letter error corrections in five districts. As-ofs peaked at just over 500 mln dlrs on Tuesday.