I took my Buggy Rifle out to my rifle range again today. This time however I had the correct .350 round ball. Shooting with a light patch and 15 grains of powder. My first shots were about 18 inches low at 50 yards.
Since the homemade front sight was purposely made too high, I also brought a small drill press vice which was clamped to the shooting bench with the intention of filing the the front sight. Filing the sight combined with raising the rear sight raised subsequent shots.
I also increased the charge to 20 grains which also raised the bullets' impact.
All in all I am happy with the results. Now I just need to focus on decreasing group size.