The key to a successful brisket crust has a lot to do with the size of the pepper chunks. Pepper is usually measured in size by mesh, and the ideal size for beef, or lamb is anywhere between 1- and 16 mesh. It's a very coarse crack, sometimes referred to as crushed or kibbled.
Lamb is practically built for smoking, especially shoulders and legs with connective tissue and fatty seams. I cook until the meat is tender.