When it comes right down to it, there is quite a bit of latitude in load development, that can be manipulated to throw better patterns.
Depending on what you're shooting, the simplist is to just use more pellets...in the black powder muzzleloading world where most smoothbores are indeed cylinder bore, the old saying is still real today:
"Less powder, more lead, shoots far, kills dead"
IMO, the modern rifle and shotgun load development have evolved to efficient top performing shells with two fundamental objectives...power and distance...sometimes referred to as "magnumitis". But if I've learned anything shooting Flintlock smoothbores, it is the stark reality that 99% of every shot I take at a crow over decoys, or a squirrel in a tree, or a turkey in front of me is usually just 20-30 yards...we simply do not need Yorktown battleship size shotshell loads for 99% of our shooting.
So explore reconfiguring your wads to fit in another 1/8 or 1/4 oz of the shot sizde you're wanting to use...and, better yet, if you focus on the fact that most shots are a lot closer than you think, you don't need large pellets with massive energy for 40-50 yards shots...#7.5's or worse case 6's do fine for most any game at these relatively close distances.
Good quality copper or nickel plated shot also adds more pellets to the pattern.
And EcoTungsten(Niceshot) gives me significantly more pellets in the pattern than either of those, but is a very expensive non-toxic for waterfowl and I can't afford to shoot it just for any old thing at $28/pound.
Smoothbores are very forgiving...forget the typical modern ballistics listings as if they are cast in stone...they are just optimized loads to include the 40-50 yard shots...you have a lot of choices to tinker with...think in terms of 25-30 yards with a cylinder bore, using a shot size that will give you more pellets in the pattern, and as a penetration test just be sure they'll blow through the metal of a stong tuna or soup can at that distance.