I use a utility knife with a brand new blade for the vein slice. You have to be sure and get between the feathers, they're like armor. Get between the feathers, up against the skin and make a nice, fast slice. Even if you don't get both veins at first, they're upside down and it'll drain, just a little slower, and you can go back to get the other vein. That happened a time or 2 until I got more aggressive with my cut, but they never even acted like anything had happened. I zip-tie their feet together, then hang over a nail in a tree. I usually hang them, then go get the knife, put in the new blade and come do it.