I have heard guys suggesting using silly putty to seal off the open areas in the action and the mag well when bedding a rifle. I hesitantly gave the silly putty a try, but I had suspicions of what may happen due to my previous encounters with that junk. When left sitting over a small amount of time, silly putty acts like a liquid. It will "melt" and spread out, almost like you would expect honey to do. So after I filled all of the voids in the action and poured my devcon, in no time the silly putty was leaking downward with gravity and falling all over the place making a mess. Luckily it did not screw the bedding job to hell, so I dodged a bullet this time. However, it is a poor choice, and I would highly recommend something that maintains its shape like clay.