I've posted this before so forgive the repeat but my experience has been different from others, especially with the 44 caliber. On the larger caliber at least I have always got the best accuracy with maximum loads. This has occurred in both modern and BP guns.
Although the Navy 36 kicks more with maximum loads it is pathetic compared to a modern 44 Magnum.
As long as you "go with the gun" recoil isn't a problem. Little women shoot the 44 Mag.
In any event, one reads all the time about target shooters using very small loads and a lot of folks just assume that's the best accuracy. Not always- nothing is etched in stone.
The reason I dropped down from 25 grain to 18 grain is because I like using pre-lubed wonder wads and they take up some room in the chamber, leaving an 18 grain load about right if the ball is to be seated close to the end of the chamber.
Why would a maximum load be more accurate? I have no idea. One thought is that slight differences in the powder charge are proportionally less with larger powder charges. In other words if you make a half grain error on a ten grain charge versus a 25 grain charge, the percentage of difference in the charge is greater with the smaller 10 grain charge. Another thought is that the full grain charge may be more stable. On this thought, the chamber is full of SOMETHING- black powder, a wad, cream of wheat, whatever. Maybe compressed powder is more even from shot to shot than a chamber with a 10 grain charge, cream of wheat, a wad, a ball- lots of variables.
But ultimately, you need to test shoot and see what works best for you. :v :v :v