I've read some 'Ole English' type verse that refers to controlling the dispersement of the shot by changing the ratio of the powder charge to the shot charge and in effect choking the barrel.
The old books and pulp weeklies are full of discourse on experimentation with the trade off of powder and shot with particular emphasis on penetration. The shooters of the 19th century were more "hands on" than we are now. Brass shells were always home-loaded and loaded paper shells made their debut in the mid 1880s, as I recall.
I have a trap out behind my barn and I blow-off a lot of el-cheapo ammo like $4.99 per box, 1200 fps 1 1/8 oz 7 1/2s; for pheasants I use $9.99 per box, 1220 fps 1 1/4 oz no. 5s. I'll bet the "choke" of my Parker GH would "measure" quite different if I counted the percentage of shot in a 30-inch circle at 40 yards for the two similar fps loads.
It takes time to shoot patterns and counting all those little holes is quite boring, thus most of the choke boring banter we hear is on the relative merits of sticking a dime or some similar bore-diameter measuring device into the muzzle and declaring the job well-done: it's Full Choke!
Someday curiosity is gonna get the best of me and I'll find out how my selected ammo really patterns...and then the manufacturer will surely discontinue it. EDM
