I of course, concur with Taylor & Bob along with all of the other accuracy shooters.
When he first built the .40, Taylor was using around 45gr. 3F and even with that charge, he was difficult to beat. That was because he used to shoot that rifle offhand as well or better than anyone else could if benching it. He's increased his charge now and is near impossible to beat - if shooting that little Kuntz .40, with the Getz barrel.
Heavies charges certainly demand thicker patches - that is a given fact, BUT - thicker patches and heavier loads do indeed shoot more accurately than light charges & especially light charges with weak patches. That would translate to 3 levels of accuracy. Thick patches and light charges shoots better than light charges and thin patches. Anything actually thinner than about .018" or .019" compressed measure, are too thin in my opinion, when using balls that are .005" smaller than the bore size.
Usually, if one has a rifle that shoots better with 30, 40, or even 45gr. than it does with heavier loads, it is due to that person using too thin a patch. The thin patch does not maintain it's integrity with the heavier pressures generated by the heavier charges. This gives fliers and poor overall shooting. The heavier charges thus cannot show their superiority.