Was at the range to sight in the temporary (load development) scope, and was shooting some .22lr in between groups. Got home, pulled the pup out of the case and OH CRAP!! A distinct rattle that wasn't there before. It definitely was from the forward half of the gun. Removed scope (no rattle there), field stripped gun and rattle still there. Debated removing forearm while shaking front end around to try to see inside, and the rattle stopped when I heard something small hit the floor. The culprit was laying right there. A frigging rimfire case that had somehow made it inside the forearm. Whew!! I was giddy with relief, but I had to share this. From now on, I will be covering my RDB whenever there is .22 brass flying around.