25 or more years back I shot a Spiller & Burr in competition for a couple of years. I shot 18 grains of GOEX 3f, .375 Speer ball, Cream of Wheat filler (don't remember how much) and used Korean war vintage Aircraft Instrument and Screw Actuator Grease over the ball. It shot a good group but was 8" or possibly more low at 25 yards, windage was good. I never modified the front sight and moved on to a Rogers & Spencer later. There was no improvement in the group over 18 grains and it opened up fast as I went down toward 15 grains. I liked the little gun except for the fact that the grip was so small that the load beat the devil out of my saluting finger even with a tight grip and my little finger under the bottom of the grip.