Yes, they are; choose wisely for leanness. Bone out the shoulder blade bone, be sure to check the fattier end and around your boning cuts for small pieces of cartilidge and bone (there was a backbone with ribcage boned off it earlier) that could clog your grinder plate.
There's a couple methods of how-to's - cut up your pork into 1-2" chunks, mix your seasoning with it then grind, or chunk up just small enough to fit into the head of the grinder, grind 1st, then mix your seasoning. Both yield the same result as long as you thoroughly mix the seasoning throughout your grind, it's whatever method works for you. I cut mine up into 1 - 2" chunks, mix the seasoning with it then grind it once through the coarse plate. I don't have a mixer so I use the grinder as the mixer. Others grind it coarse once then add the seasonings and mix, either by hand or with a mixer. Either way results in a coarse grind mix with seasonings spread uniformly throughout. Then, put into the stuffer, load up your horn with casing (rinse and soak 1st; I soak mine before starting to cut up my pork. Add a few drops of white vinegar to soften the casings). If you just rinse and stuff your casings can be tough to bite into. Pack medium full; you'll need some wriggle room to twist into links. Pinch every 2 or 3 inches and twist into links, twisting to the left on one, then to the right on the next, then left on the next, etc. so you're not twisting one link tight while untwisting the previous one. IMMEDIATELY after making your sausage give one or two a heat bath.. cook 'em up to try them! Nothing better than frying up your own home made sausages! Immediate gratification!