Dan: There are some things you can do to improve the accuracy of your bess, besides working up your load carefully. Make sure the barrel is beded evenly, so it does not twist during recoil. Make sure the rings are not too tight, putting pressure on the barrel.
That lug makes a pretty lousy front sight. Some men file or grind down a portion of the top of the lug to make a narrower front sight, but still retain the keeper function of the lug for their bayonets. And, some put some kind of rear sight on the gun, one that can be removed so that the gun is restored to its traditional configuration.
Polish the bore, too, with lapping compound if it shows any tool marks in it.
Finally, tune that lock so you aren't crushing flints. Besides the costs of flints, the vibrations from that impact rattles the gun and often spoils a good shot. The trigger pull should be about 5 lbs, too, for good hunting accuracy. Most are much more than that. First polish contact surfaces, and get rid of any thing in the lock that is rubbing against the lock plate, or some other part where it is not suppose to do so. All that contributes to slow lock speed, and a slow time for the cock to fall and create sparks. Once you have all the parts moving freely, you can set about tuning the lock. The Frizzen should open with no more than 3 lbs. of pressure placed on the top of the face, and pushed forward. The mainspring should be about 15 lbs. but can even go less. Most are over 30 lbs, and hurt your fingers to cock the darn things.
