Yes, the model does jitter that much. No, I don't know how to fix it, but luckily, it doesn't affect gameplay.
This is a reskin for the Portal gun that replaces the Portal gun with the Beta PhysCannon/Gravity Gun from Half-Life 2. It acts as a DLC pack for Portal 2. The enclosed .txt file in the folder contains info on how to install it. Hope you enjoy it! Special thanks to LambdaCore21 for helping me to get this working and more special thanks to OddDoc for leaking the Beta PhysCannon from the Source Developer Repository!
Map used in the screenshot: Steamcommunity.com