grinding brake drums

I own a 1995 Pontiac Grand Am V6 3.1L with 167,000 miles on it. Yesterday, I did a full brake job. Now, my car had disc brakes in the front and drums in the rear. I replaced the rotors and brake pads in the front. However, I felt like the brake shoes in the rear had some good life left in them so I just replaced the drums and left the old shoes on. I took my car out to bed the new brakes in. The front brakes (disc) bed in perfect and are working great, but the rear brakes (drum) make a grinding sound as if there is a rock in between the drums and the shoes. Maybe that is the problem. Does anyone know what else it could be? It is almost as if the rear brakes don't fully engage. The grinding sound is more prevelant with applying the brake pedal, but the sound is still there when I let off of the brake pedal as well.

Maybe a spring or something isnt attached correctly dragging when applying the brakes.
Probly should have changed the shoes too.
Were the shoes worn evenly on both ??

Plus new drums are pretty agressive on pads when you first install them.
Might not hurt to pull one side off and see if anythings rubbing, or whats going on in general.

I pulled off both drums. An adjuster spring on the passenger side was busted. I bought a springs replacement kit for $7 and I believe I have fixed the problem. Thank you.

just curious, why did u replace brake drums??