My sons were wrecking the L3 buttons on their DS3 controllers while playing COD. While sprinting within the game (pressing the L3 button), the character would start performing random actions such as switching weapons, shooting and reloading.
Here's a link with pics on how I fixed that specific issue.
It's free and fast
***Perform the following actions at your own risk. I am not responsible for any damage or injury while performing the actions below***