Cyl/Full or IC/Full covers the gamut and I suppose gives the gun the most versatility, but the 16 gauge doubles I've owned that have been the most reliable with an ounce of shot and in keeping with the inbetweener nature of a 16 gauge double have been in the .007/.013 range for the respective right/left barrels. A 16 is best when it's not trying to be a 12.