Twist barrels would be on the lowest grades 0 or 1. In those days the Qualities in these lower Grades were differentiated by grip style and gauge. A 10-gauge was $5 more than 12-gauge and smaller and a pistol grip was $5 more than a straight grip. So, a Grade 0 gun could be a Quality R, S, T or U; and a Grade 1 with Twist barrels could be a Quality N, O, P or Q. Confusing enough!!