MARINE CORPS AIR GROUND COMBAT CENTER, TWENTYNINE PALMS, Calif. -- Job proficiency is one of the most important aspects of being a Marine, and that's doubly important when a Marine's job includes directly supporting the infantry in combat.

To that end, Marines from "D" Co., 3rd Amphibious Assault Bn. spent Feb. 27 and 28 with their amphibious assault vehicles on the firing line getting familiar with their weapons, turret-mounted M-2 .50 caliber machine guns and MK-19 40mm rapid-fire grenade launchers.

Range time is the second "building block" to combat effectiveness, said "D" Co. commanding officer Maj. David Reeves, 35, of Ellicott City, Md. The first building block includes knowledge gained in the classroom and in simulated marksmanship training. Marines are able to take what they learned in class and on the range and employ those lessons during Combined Arms Exercises and, ultimately, on the battlefield.

"This week we got to employ our whole up-guns weapons system," Reeves said. "This is huge training for us. It's the backbone of what we do in support of infantry Marines."

"D" Co. 1st Plt. leader 1stLt. Erik Morton, 27, of Jacksonville, Fla., explained that the opportunity for new Marines to get some trigger time is extremely valuable.

"About 80 percent of this platoon is brand new," Morton said. "The last time most of these Marines fired anything was in the school house. This gets them back on the weapons and firing out in the desert."

Morton said he was pleased with his platoon's performance on the range. He added that live-fire training also gives the platoon's new section leaders a chance to hone their skills.

The skills of every Marine in the company will be put to the test soon, when the unit takes part in CAX 5, which kicks off at the end of March. Training on the range also keeps Marines constantly ready to deploy to the world's trouble spots if necessary.

"We're just going over the fundamentals of the up-guns weapons system, like loading, unloading, using the sights, basic stuff like that," said Cpl. Gordon Dodge, 20, of San Diego, "D" Co. AAV crew chief. "This is sort of a refresher for everyone. We haven't been on a gun shoot on our own in a while."

Of course, when dealing with weapons such as the M-2 and the MK-19, brushing up on fundamentals necessarily includes blowing scrap armor into tiny pieces. Marines' reactions were pretty much what one would expect when healthy amounts of destruction are involved.

Or, in the words of "D" Co. AAV crew chief LCpl. Jesus Lira, 20, of San Antonio, after scoring a number of direct hits, "This is some motivating training!"