Stay at the start position and use the M240 machine gun and Barrett as your main weapons. You first need to take out 3-5 of the juggernauts without the Barret so hold the grenade launcher and the M240.

Start at the load out mat and position a claymore under the longer stairs facing out through the steps toward the mat and another around the corner of boxes where the juggernaut will not see it as he decends the steps toward the load out mat. Go back around the corner down the shorter stair toward the boat where you will have a view of the juggernaut as he descends the stairs. When he sets off the claymores he will crouch down a bit and hit him with one round from the grenade laungcher and switch to the machine gun. Hit him hard with the machine gun here and you should be able to get him easily before he has a chance to recover.

Repeat till your out of grenades for the thumper or claymores. You want to hit a few so you have enough ammo in the Barret to take out the rest, give yourself six to seven shots per juggernaut for the rest of them.

Once you have taken out 3-5 of the juggernauts position yourself under the stairs with the stairs between you and the loadout mat pointing your Barrett upwards through the grating of the stair landing above you along the upper set of stairs. You should have a line of sight as the juggernaut moves toward the stair well from the level above and be able to start shooting him before he starts down the upper half of stairs for the two parts coming down to your level. You have two sets of stairs to shoot at him and should be able to kill off at least six or seven juggernauts without too many piling up and ruining your sight. If you get too many piled up simply wait till they get to the landing directly above and shoot as they turn toward the lower half of the stairs.

I have easily killed off all juggernauts on the stairs after getting rid of a few on the landing by the loadout mat, just shoot using the Barrett and the stairs themselves as cover. The Barrett easily goes through the grating from underneath as well as between the steps and they will never get a shot off.

Its getting those first few without usng the Barret that gets tough but using the M240 and the Thumper with claymores works.