CAMP PENDLETON ---- While artillery men generally consider blowing things up a slice of heaven, the loud booms emanating from Camp Pendleton day and night of late has left many outside the gates saying they are experiencing a slice of hell.

"I don't object to noise during normal hours and I don't mind it up until about 10 p.m., but they need to have a little consideration for people who need peace and quiet so they can sleep," said Allen Mortend, a longtime Oceanside resident who lives just outside the base gates.

Base officials say they have received dozens of noise complaints from Temecula to Carlsbad to sometimes San Marcos as the artillery barrages go on.

On Monday, they invited reporters and a couple dozen other civilians to witness crews from the 1st Battalion, 11th Marine Regiment honing their targeting and firing skills and to explain why the shells are being fired round the clock.

"It's the sound of Marines training, and we know it's loud," said Lt. Col. Bob Manion. "But many of these units are deploying soon, and in the artillery there's a low tolerance for mistakes. You can't simulate it; you have to get out and do it."

Manion's boss, Col. Larry Holcomb, the battalion commander, put it a little more succinctly.

"We are a nation at war, and sometimes people forget that," he said.

The unit has been practicing its deadly skills since a week ago Monday. The firing continues at night, battalion commanders said, because their troops need to be proficient in the dark as well as daylight.

Crews are firing M198 howitzers and M777 cannons, a newer version the battalion is incorporating that weighs about 9,200 pounds, nearly half the weight of a howitzer.

They're mostly firing 155mm shells packed with TNT that can be shot anywhere from 2.5 to 18 miles.

The shells weigh between 95 and 135 pounds and come in varieties that include one that lights up the night sky, one that explodes overhead and regular ones that explode on impact, raining shrapnel in a 75- to 100-yard radius.

Heavy artillery was more commonly associated with World Wars I and II as well as the Korean and Vietnam wars. In more urban environments such as Iraq, artillery has been used sparingly. It's the same in largely rural Afghanistan, but is still employed when the military can safely target groups of insurgents without harm to civilians.

"We use it when it's more advantageous to give the enemy something to think about," Manion said. "Our job is to clear the way, and when Marines are pinned down, we are good at disrupting that."

The men who actually load and pull the lanyard that fires the shell say they love what they do.

"It can be a little bit chaotic, but I think it's a lot of fun," said Sgt. Steven Castro.

A relative newcomer to the unit, 2nd Lt. Pat Cullinane, who arrived in March, likes the "sound of freedom" and destructive power of the artillery.

"I like big explosions," he said.

During Monday's exercise, crews poured round after round into a sloping area less than 3 miles from the firing position. The shells threw huge clouds of dust into the air as they hit, with the noise that has been alarming some and disturbing the sleep of others echoing off nearby mountains.

For people such as Mortend who live close enough to the base to hear the echoes of those explosions, it's all becoming a bit wearying.

"I've spoken to the Marine Corps and asked them to arrange to have the exercise in an area that doesn't affect hundreds of thousands of people," he said. "Policies need to be reviewed from time to time, and with all the homes that have gone up around Camp Pendleton over the years, it's time to consider again when and where they should be doing this."

Base officials say they do their best to alert surrounding communities to the exercises, sending out noise advisory news releases to local media outlets and posting regular updates on the camp Web site, http://www.pendleton.usmc.mil/information/noiseAdvisory.asp.

Call staff writer Mark Walker at 760-740-3529.