Part of the evolution really. Being familiar with hammer gun I can just look at them in general and have a good idea of their age. Tall hammers in early guns because that was what shooters used to percussion and flintlock were familiar with. Then hammerless guns came in and hammer guns from this later period often advertised as a selling point 'hammers below the line of sight' when cocked. Hammer guns were being made well up until the second world war and could be had with Damascus barrels; at extra cost, and Jones type underlevers too. But almost all had 'hammers below the line of sight'.
This is the only area that Diggory seems to have neglected a little in his book; that is the later built hammer guns which were often quite plain and 'agricultural' but still a great product. Lagopus.....
