Installing Kelsey Hayes Caliper Pistons ?

Let me ask you this..could i re-use my pistons and just run some smooth sand paper over them? I bought this whole brake setup freshly rebuilt about 16 years ago..new rotors, pads and rebuilt calipers. They spent the first few years in my house till i got my garage built and then they stayed in there until a few weeks ago when i FINALLY got around to doing this job. SO, i dont think they are in too bad of shape inside but i do think they are stuck because i took the car for a first drive yesterday after installing them and i have to literally stand on the pedal and it just barely slows down. Cant even lock them up in my gravel driveway!
I don't think this is a caliper issue, maybe best to start a new thread