I use 25 yards only to start the sight alignment operation. For load testing, I find 25 yards next to absolutely useless. Any decent smoothbore with only a front sight, will cut a single hole for 4 or 5 shots,at 25 yards.
50 yards is where things start to get interesting & loads begin to sort themselves out. Further, as in 60 to 75 yards is even better for load testing. 25 yards proved nothing.
In BP ct.g guns, 200 to 300 is a better starting place.