Sorry that I didn't answer you sooner, but I've only injected feet a few times and I thought you'd get advice from some more experienced guys. You inject the feet so that they will stay plump, otherwise they will shrink. I use a product called Fantastic Cast and inject it with a hypodermic needle. Both are available in taxidermy supply catalogs. The Fantastic Cast is like a two part resin. If the feet are dried out when you first start skinning the bird, you may want to inject the feet at that time with some water. This will plump them up and they should soften up good by the time you are ready to inject them with the resin. Start at the tip of the toe and see how far up it goes. You may have to inject a toe a second time further up to get the water to go all the way up. Just don't poke too many holes in the feet or else later a lot of resin will leak out. If you inject the feet with water first, try to reuse the same holes when you inject the resin to reduce leakage. When you are all done positioning the mount you inject with the resin. First tie a string tight around the base of each leg where the feathers start. This will keep the resin from bleeding up into the rest of the mount. Then you inject each of the toes and the lower leg just like you did with the water. Go slowly so that it doesn't come flying out of any holes onto the feathers or into your eyes. When you're done you can clean any resin off of the feet with acetone. When it's all dry you can remove the string. As far as bill shrinkage goes, you can avoid it by using artificial heads. The heads are also nice because you paint the bill before you assemble the mount, this way you don't have to worry about getting paint on the feathers.