I have several Lee molds and haven't had a problem with them. For the money I consider them to be an excellent buy.
Buy the softest lead you can find.
Lead made from salvaged pistol/rifle bullets from a shooting range will be quite hard.
Lead from roofing companies will be quite soft.
As the others have mentioned, if your stuck using a hard lead you may have to reduce the thickness of the patch you've been using.
This is needed because the lead roundball won't deform when it's started into the muzzle.
The catch here is, the patch will still need to be deeper than the rifling grooves on your guns to seal the grooves off.
For most factory made guns, this isn't a big problem but if your shooting a rifle with a barrel made by Rice, Getz, Douglas, Green Mountain or other muzzleloading barrel makers they will have rifling grooves .012 to .016 deep.