I would appreciate anyone's opinion / knowledge / experience with this subject: Several years ago I acquired an original 1863 Springfield rifled musket in very good condition. Bore diameter is roughly .585. Research indicated the original charge was 50 grains, increased to 60 grains late in the Civil War due to concerns over powder "quality". One book contained many sketches of test firing results showing nice groups around the target center. Grain size was thought to be close to 2F, so I started using a .575 minie over 50 grains 2F, bench shooting at 100 yds. Surprisingly accurate considering it is 158 years old, shots with a clean barrel were high and to the left by a few minutes with a distinct group. Switching to .582 minies, same result except the groups were tighter. These rifles were subject to proof firing before Government acceptance, so it's hard to believe it would have left the factory shooting like that, so I switched to 40 grains of 3F which brought the groups down to the aiming point, still with a little left bias. This was a 20% reduction in powder weight, with a finer grain size. Still experimenting, but my present theory is that our powder is hotter than theirs was. What are your thoughts?