on page 9 for trade or treaty firearms of the american indians 1600 -1920 by RYAN R. GALE....trader joseph isbister wrote in august of 1740; the guns are good but have too much wood in their stocks,the indians liking them more slinder and to be free of knots,and also to have the guard larger it being usual to draw the trigger with two fingers which our guns will not admit of...this is a great book for the study of northwest trade guns...real letters from traders in the forts...the mitten idea seems logical but its not the real reason according to traders in 1700s