So went to the range today with a few friends, one was shooting a s&w sigma in 9mm. while shooting this gun, the plastic insert/plug that goes into the bottem of the grip, and sits flush with the magazine came out. My question is, what casued this? Can they order a new one? Is it very important? I could not see where it would be used ofr anything besides being a filler. I have a sigma in .40 and mine has never came out. So any advise I can pass on to them would be great.