Are you sure that name isn't H. M'Clallen, rather than M'Callen? There was a Hugh M'Clallen, who worked in Auburn, New York, 1829 - 1860. He was born in 1792 and died in 1860. He was apparently a fairly prolific maker, employing several other gunsmiths in his shop. Several of his guns are pictured in Vol. 3 of the Swinney/Tom Rowe books, THE NEW YORK STATE FIREARMS TRADE.