Pinch the bullet button's plastic housing firmly.
Pull up on the bullet button housing, as shown. If it's an early-generation bullet button which can't be pulled up on, you don't need to worry further.
This bullet button is pulled up as high as it can go.
Lift the bullet button either upwards (towards the upper receiver) or downwards (in the direction the mag would be released). Due to tolerances within the magwell, a defective button will actually 'cam' over just slightly, enough to engage the threads on your magazine release. The magazine catch will then press in just as if the original magazine release were being used.
Press down on the bullet button, while maintaining pressure at an off angle so that if the threads are captured, they will remain captured. Your magazine will now release if and only if your bullet button is defective.
Please note that this is by no means a common issue with the bullet buttons. I have seen one confirmed case, and heard of one other with an earlier version of the bullet button. Should you have an issue with your bullet button, contact the manufacturer and request a replacement. Or if you wish to repair it yourself, simply take the bullet button out. You will likely see a burr on the bottom hole, where the mag catch passes through. Removing this burr should remedy this issue entirely. -- SeanNewton - 18 Jan 2010