with my rifles, sometimes adding between 10-20 grains will help accuracy. Heres some examples ive had happen.
winchester x-150 shooting a 360 grain minnie, 80 grains pyrodex rs will give me 1 1/2" groups, but if i add 10 grains for a total of 90 grains pyrodex, my groups will open to 4" @ 100. This rifle normally shooting 5/8" groups @ 100 with 385 grain hornady great plains bullets and 80 grains of either triple 7 or pyrodex rs.

My deer creek sidelock in 45cal shoots a 225 grain powerbelt with 80 grains triple 7 and will shoot a constant 7/8" group @ 100. But when using pyrodex, it will "only" hold a 1 1/2" group.

Winchester x-150 when using powerbelts WANTS 120 grains Pyrodex RS loose powder with either a 245 or 295 powerbelt and it will hold a 1" group. With 100 grains or under, it will hold steady 1 1/2" groups.

It just takes time, powder, bullets and patience to get the right load that your rifle prefers. I have a little over 1200 rounds through my winchester and finally know what it likes. 4 years later haha.

Best thing is exactly what you said yourself in your post.... Experiment with loads.