FSJ,
The difference in the 7 1/2's and 8's in our forest has a lot to due with the density of the forest habitat. Early season when the habitat is like the Viet Nam Jungle here in Pa, Ny, Vt, NH and WVa the 7 1/2 shells push the habitat a lot better for downing flying Grouse. In fact 6's work even better for shooting thru the edges of big Hemlock Tress and Giant Grape Vines. When the leaves are partially down and a gunner can get a closer better view of the Grouse, the 8's work well. In fact at this time I go to the SpredR shells with great success.
This also holds true for different double gun use, in the very early season I have been known to use my 12 Gauge for cutting thru the thick foliage, using Fiocchi hi grade quick 7 1/2 and 6 shells, then when the leaves are partially down, I go to the 16 Gauge, with SpredR shells, 8's under the 1st trigger and 6's under the back trigger. When the leaves are almost completely down I use the 20 and 28 gauge double guns in the same manner.
Ryman Gun Dog
L.C. Smith Man
Ken Graft watches his Gordon Setter Ruby on Point, at the edge of the thick forest, with his 16 Gauge Parker DHE.
