Speaking only of over/under guns, Beretta gives the height of their 20 gauge frames as 2 1/8 inches and the baby frame as exactly 2 inches. Not a very noticeable difference until one handles them. However, my baby frame 28/410 gun measures 53.7 mm or 2.11 inches tall. Also, the CSMC A-10 small frame guns measure 54.5 mm or 2.15 inches tall for their 20/28 gauge guns.