Keep a Distance
Since Juggernauts tend to charge the player, maintain a distance from the foe. When the Juggernauts first hit the area, an ominous theme plays, giving the player time to retreat to a safe location. Unfortunately, the Juggernaut will always move toward the player, requiring constant movement on the player's part.
In the "Estate Takedown" level, there are an infinite number of Juggernauts that spawn at random intervals. Keeping a distance from multiple Juggernauts is difficult, but focusing on one at a time is ideal.
Weapon Choice
The best weapon against a Juggernaut is the Barrett .50 Caliber, which can bring down the enemy in three to five shots. Other weapons are no where near as effective. It requires nearly 80 rounds of assault rifle fire, five torso shots from the Intervention Sniper Rifle, 14 shotgun hits, or five to six direct hits from the M203 40mm Grenade Launcher to defeat a Juggernaut.
Furthermore, only flash grenades can stun a Juggernaut. The Juggernaut will continue its advance towards the player if attacked with any other weapon. Since most weapons need to be reloaded frequently to kill a Juggernaut, it can be easy to become swarmed by enemies.
Utilizing Cover
Should you be attacked by a single Juggernaut, it is possible to crouch and hide behind an object such as the large ammo crate in the "High Explosive" level. This creates a wall between the Juggernaut and the player. Only a few bullets will hit the player, and the Juggernaut's head becomes an easy target. However, this does not work against multiple Juggernauts.
In the "Snatch &Grab" level, a player can hide under the dismembered plane wing. This provides significant coverage, as the Juggernaut will not try to shoot through the wing or crouch down to attack the player. A second player can then draw the Juggernaut towards the hidden player, who can then easily take down the Juggernaut.
Teamwork
The most effective strategy requires two players. With double the firepower, each player is able to conserve ammunition and deal damage to the enemy. If one player uses a sniper rifle and the other uses an LMG, it becomes much easier to bring down a Juggernaut. The primary gunner should line the Juggernaut up and cause a distraction, while the sniper takes aim at the Juggernaut's head.