I recently posted a thread on the G4 cartridges loaded by the A20 Weapons Training Battalion at Quantico. They were supposedly loaded to a higher velocity than the M852, something the Marines were famous for.
Today, I chronographed a few of the G4 cartridges and they are indeed hotter. A whopping 2799 fps! That’s 172 fps faster than the M852.
The USMC was instrumental in developing the M118 LR and it’s easy to see why the first LR cartridges were loaded to 2700 fps. Even that step-down in velocity must have been hard for some of the more enthusiastic Leathernecks.