Halcon,
The forearm comes a little loose so that mud, dirt and the like won't mess with the action. However, like you I didn't care for the rattle too much. I found that you can tighten the slide bars on the forearm with an allen wrench and loose the rattle. It only takes a VERY SMALL turn, NOT TOO TIGHT. About 1/10" at the most I would figure. Just in case your buddy would like to get rid of that rattle