Conical bullets require a rebated heel if they are to be accurate in a cap and ball revolver. Otherwise, it's just too difficult to get the bullet started straight in the chamber with the lever.
The old timers knew this; all of the conical bullets used in cap and ball revolvers had this short, instepped "heel" around the base of the bullet, that slipped into the chamber. The rest of the bullet was oversized, to ensure a good seal.
It's nearly impossible to get a standard bullet started straight in the chamber, it wants to tip to one side or another.
Lee makes a bullet mould to cast an excellent roundnosed bullet designed for cap and ball revolvers. It has the heel to start in the chamber. Its driving bands are also progressively larger, from the bullet's base forward, to help guide the bullet straight in the chamber while ramming.
I don't know if anyone sells these bullets, but since you cast your own bullets already then I'd suggest you buy a Lee mould made for the .44 cap and ball.
Lee used to make a .36 version of the same bullet, but hasn't offered it for some years. I have a Lee .36 mould, but I've not found the bullet as accurate as the .44 version.
Overall, I think you'll be more satisfied with plain, ol' lead balls in your Colts. They're easier to load and almost always more accurate than any conical bullet.
Also, note that if you use a conical bullet in a cap and ball revolver, you need to reduce the powder charge to compensate for the greater volume that the bullet occupies. This results in a lower velocity.
The heavier bullet, with lower velocity, will strike higher on target than the ball.