shotguns
http://www.chuckhawks.com/shotgun_recoil_table.htm
rifles
http://www.chuckhawks.com/recoil_table.htm
the others are right...stock design, weight etc all make a diffrence in felt recoil...plus shotguns and rifles have a diffrent recoil due to the rate of compustion...but those 2 put it in numbers for ya..