MacDILL AIR FORCE BASE, Florida (CNN) -- No piece of equipment is more crucial to a soldier in the field than his rifle. And America's most elite troops are about to get a new series of rifles designed for their unique and dangerous missions.
CNN was given an exclusive look at two new rifles for an elite group of U.S. troops.
"The difference is, I'm gonna have a weapon that's gonna fit the situation," an Army Ranger staff sergeant said.
Special Operations Command (SOCOM) is about to start training its SEALs, Green Berets and other Special Operations troops in the use of Mark 16 and Mark 17 rifles.
Within a year, the new rifles should be in action against terrorists and insurgents in Iraq, Afghanistan and hot spots the public may never hear about.
The usually secretive SOCOM gave CNN an exclusive chance to see and even fire the new weapon recently at its headquarters near Tampa, Florida. 
Watch a preview of the new weapons »
The contractors working with SOCOM to develop the weapon say it is more versatile and more accurate, jams less and lasts longer than the current rifle used by many Special Operations troops, the M-4.
The Mark 16 (Mk16) fires a 5.56 mm round, the same size used for decades in M-16s and M-4s. The Mk17 fires a larger 7.62 mm round that is used in some U.S. military machine guns, but it's not the same round as in the AK-47, the world's most widely used assault rifle.
Both of the new rifles are designed to kill regardless of the situation.
"Whether that's a soft target, a guy without body armor, or whether that's an enemy force within a vehicle that you need to shoot through a window or the side of the vehicle and you want to ensure that round is not deflected," said Tucker Campion, a retired Navy SEAL who now is a civilian contractor working on the new rifles. "We want a round that, when it hits the enemy soldier, provides the maximum amount of damage."
Even though they fire different-size bullets, each rifle is largely interchangeable with the other. By changing only a few parts, including the bolt and the barrel, a soldier can switch from a gun that fires the lighter 5.56 mm round to one that shoots the heavier 7.62 mm round in a matter of minutes.
That's just one example of the rifle's versatility. Each gun comes with three interchangeable barrels, and each gives the troops a specific advantage.
"If you were going to clear an urban environment, buildings, rooms, you'd probably throw the short barrel on there," the staff sergeant said.
CNN is honoring the Ranger's request not to identify him, because in battle, anonymity is crucial for Special Operations troops.
"If you're in Afghanistan and you're walking in the mountains and the hills and all that, and your distance is going to be a lot greater to the enemy, and you're probably going to want to throw the longer barrel on there so you get that extra reach," the Ranger said.
Even though the rifles fire the same bullets as existing weapons, they are designed to be much more accurate.
"If you look at a current inventory assault rifle, you get 350 to 400 meters," Campion said of their range of accuracy. "Put a long barrel in (the new rifle), and now you're at 6 to 7 (hundred meters). So we're extending the standoff between us and the enemy." A longer standoff means an American can shoot an enemy soldier from farther away; thus, the American is safer.
One of the main goals was to design a gun that lasts longer. Campion says the M-4 is designed to fire 6,000 rounds over five years. But the Mk16 and Mk17 were designed for Special Operations, who are likely to fire 6,000 rounds in less than one year. The new rifles are designed to handle the greater rate of use and last twice as long.
The design changes that make the Mk16 and Mk17 last longer also make them more reliable. Nothing is worse for a GI in battle than for his rifle to jam at the wrong moment, but it happens with all kinds of guns. These new rifles are designed to reduce those jamming problems as much as possible.
The new rifle also comes in a Mk13 model, which includes a grenade launcher mounted below the barrel.
To those who will use the rifles in the field, what they need first and foremost from the new weapons is success. E-mail to a friend 
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