That box is really for range shooting. I use the little camo "bag" with premeasured powder charges for doves. Most important thing in that pic, to me, is that loading rod I made from a hickory ramrod blank and an old solid brass doorknob. The tube beside it is 1/2" metal conduit. I flared the top end a little, and hammered the other end into a point to make it easier to push it into the ground. For stationary shooting, such as doves or clays, it is invaluable.
I used a possibles bag too, when I used the gun for quail, so as to travel light. Always wanted a good shot snake and powder flask, tho'.
One cool thing about the Manton is that it has the original ramrod. It has a brass tip that has a knurled cap. When you unscrew the cap there is a wad screw underneath to be used for pulling wads when you want to unload it without shooting.