Disappointed - Killer Innovations Velocity Glock 17 Magazine Extension

This is the only product from Killer Innovations that I have been disappointed with. When the mag is fully loaded, the rounds rattle around like crazy. The spring also needs to be taken out and stretched frequently if you want your slide to lock back after the last round. Fortunately the design does make it easy to remove the spring quickly. I have 2 of these and they both do the same thing. They do look great and were very easy to install. I just would have expected better for the price. All of the other products I have from Killer Innovations have been fantastic so I was surprised that these fell short.