mmmmm.....thats right and i am thinking about it a lot since my forearms are weak...
The best way, is to use straps, then hit forearms separate. If you your shoulders/back can lift more than your forearms, you are haulting their progress. Do a few sets of forearms per week and it offsets the strap usage, plus, builds a fatter forearm. You can hit forearms best through regular exercises, they should be hit separate. Even though many bodybuilders don't do them, they would most likely be better if they did. Does Priest work forearms? Regardless, this has worked well for me.