The purpose to the buffer is to fill the voids in between the relatively large shot in a turkey load. The buffer helps keep the shot from being deformed by the sudden acceleration, trip down the bore and through the really tight choke. By preventing pellet deformation, the buffer helps the shot stay round, fly straighter and acheive tighter, more consistent patterns.The buffer used is usually some kind of ground up plastic and has a lot of static cling. It sticks to the outside of the plastic hulls throughout the loading process. That is why you see it on the shells in the box. Even if some does leak out, it won't hurt anything (ie. the shells are still OK to shoot). If you want to avoid any leakage, look for factory shells with a sealed crimp.