Originally Posted by Kisara
When you shake a regular buffer, you will hear/feel the weights inside. My Colt 9mm's buffer feels solid. You hear and feel nothing.
In Colt Armorer's class, you will learn that those loose weights inside the buffer are there for a reason. When the bolt carrier and buffer are starting to move forward, the weights inside the buffer slide towards the rear due to inertia. When the bolt hits the barrel extension and starts to lock up, the loose weights inside the buffer slam forward, helping give an extra kick to ensure the bolt seats properly. You do not get that extra reliability benefit in the 5.56 when using a solid 9mm buffer.
The SAW Sales reliability package includes a H buffer with heavier buffer weights, but I forgot what Tina said the exact weight was.