Try using alcohol - denatured, not drinking. It's usually pretty effective at removing latex paint and should break down the primer. If that's not sufficient, try a fine wire wheel in a drill. Make sure it's one of the finer wheels; the medium and coarse will likely stretch the hardware...
I'm new to this whole process so I've come here to read and learn. Right now, we have no chickens but will be moving to a piece of property with family members who currently have 8 ladies. I know they're ladies because they don't crow like a rooster and they all lay eggs. See, I have two key...