Olav @ Firearms and Training has taken photos of the internals of his Z-M Weapons LR300 (now manufactured by Para Ordnance as the Tactical Target Rifle) and explained how it works.
This shows a close up of the bolt carrier group. The gas key is staked. Notice the extra vents for gas to escape from, his allows the gun to run cooler since a lot of the gas and crud vents out of the gun. Also notice it’s missing the portion of the bolt carrier that sits against the buffer which saves on weight. This also means less recoiling mass.
Read the article here. I highly recommend it.