The most familiar item in the Army's arsenal is getting an upgrade. 

The M855 bullet was designed in the 70s -- and has been in use since then, despite some complaints from soldiers that it's often less than effective .The new M855A1, which the Army demonstrated Wednesday at the Aberdeen Proving Ground in Maryland, is deadlier, faster, and may soon replace its older cousin.

The new ammunition is notable for being "green" for one thing; it's lead-free, meaning the new ammo is environmentally friendly, the Army said. The military began providing the lead-free round last June to U.S. soldiers in Afghanistan

A live-fire demonstration was held Wednesday morning at the post. Soldiers fired the new and old rounds, as well as a third type, to compare the performance of all three on identical targets. The targets included a parked vehicle, steel plates and building materials.

Army officials acknowledged that the M855 "has not been providing the 'stopping power' the user would like at engagement ranges less than 150 yards," according to a 2005 briefing, the Army Times reported last year.

But ballistics experts point out no bullet is perfect; the new rounds won't be substantially more deadly, in other words.

“There is not a bullet in this world that will do that,” Dr. Martin Fackler, former director of the Wound Ballistics Laboratory at the Letterman Army Institute of Research -- who also served in the Vietnam War as a combat surgeon -- told the Army Times. “Even if you take the guy’s heart apart, he can still shoot back at you for 15 seconds because he’s still got enough oxygen in the blood in his brain to do it.”

The Army says the new ammunition is the first developed as part of a "greening"' effort for small-caliber ammunition.