I just received and installed the same frame insert in my Shield and found that it caused a problem. With the insert fully inserted into the frame it caused a very slight bulge in the frame of the pistol where it contacts the very bottom of the back of the magazine when it's inserted into the pistol This in turn caused the magazine to not fall free when the mag release is pushed. In order to remove that bulge I had to file down the three little ridges on the Pearce insert so it would not cause that bulge. It still inserts tight enough to not work loose (I hope). By the way, I only paid $6.50 for mine and I bought it at the same time as the Pearce pinky finger mag extension which I really like.
