Knocking noise when brakes applied

I need some help. I have a 1965 Dart GT with a Charger 273 and 904 transmission. The other day when I applied the brakes there was a knocking sound coming from the front of the car. Has been about two years ago, wheel cylinders, shoes, springs, and had drums turned. Seems like I read somewhere that this could be caused due to the brake drums not being turned correctly. If the drum has groves like a record then this would cause the knocking sound when applying the brakes.
Have not had this problem until this past week. Any ideas?