I also agree as far as 'typical' main charges go...however, it's worth clarifying that it doesn't mean 4F can't be used downbore at all...after all, Hodgdon themselves advertises putting 5 grains of 4F down bore as an 'ignitor' charge to improve ignition when using Pyrodex;
Also, another example I've personally tried is a small 25-30grn charge of 4F in a .45cal rifle...makes an excellet plinking load if you just happen to have a bunch of 4F to burn up.
But to be clear, I also agree it is not advisable to use normal size charges of 4F as a main charge.