A few headshots from a sniper rifle are the best way I've found to kill them. Once you get
one shot on their head, they become stunned for a bit making the next few shots easier. I
still have yet to beat the mission where you can only use explosives to kill 10
juggernauts though, because you're either too close to the juggernaut and the grenade
doesn't explode, or the RPG will shoot at the sky if you aim at the ground, and spamming
grenades while near an ammo crate still gives a chance for them to recover fast for
whatever reason.

~ Modern Warfare 2 GameSpot Forums

The Best to kill them is throw a flashbang and the juggernaut will become stunned giving
you time to shot it with a sniper rifle, if it begins shooting at you again just do the
show process. Throw flashbang and shoot it until it's died.

The way I beat it was to place two claymores next to each other, lead the Juggernaut on
top of your claymores shoot them it should kill them instantly making the Juggernaut look
awefully silly. resupply place your claymores find the next one run back and repeat. ^_^
hope this helps

For the favela one with the 10 juggernauts you need to do two player to do it on veteran.
Go to the house on the left and have one person stand in the door and get downed while the
other person headshots them with a thumper for an insta kill on them. Then in a break in
the juggernauts revive him till all 10 are done. For the sub base one you should take the
barret 50 cal and go up the stairs till you get into the open and camp on the little
wooden outpost shooting the barret at their heads and shooting thumpers in the distance to
make them spawn otherwise they wont spawn

For the oil ring level its best for both people to plant claymores and then one entice the
juggernaught out and the other is hiding in wait behind the claymores. Make sure you have
a long clear space where you can hit him as many times as possible before he gets close.
Claymores are the key though plant as many as possible but hidden because if the
juggernaught sees them he will shoot them. 2 Claymores in one place is double the force as
well

just headshot them with a thumper. instant kill everytime

Run and Gun, with all the armor Jugernots are not that fast, but they are persistant, keep
running and get them to chase you, wait for them to come around corners and bombard with
flashbangs and explosions.

just shoot them in the head a couple times

Distract and then headshot with thumper

You guys are all wack! Roughly 3 head shots with the 50 Cal. Or 4-6 body shots.
Intervention 4 headshots or 5-7 bodyshots. Thumper requires only one direct head
shot(strategy used to beat High Explosives). 9 Clay mores. Or 9 C-4s. I wouldn't waste my
time with anything else unless you have a semi or auto shotgun or M240 full
clips(Headshots). YOU DONT NEED 2 PLAYERS FOR ANY SPEC-OP!! EXCEPT the required ones(2
ops). I beat EVERY Spec-Op VETERAN AND SOLO!! So don't give me that" you have to beat
Armor Piercing and High Explosives with 2 players" BS!! I've beat EVERY SPEC-OP SOLO AND
ALL UNDER EST Completion time and quite a few under IW Best time!! ALL VETERAN AND SOLO!
So it is possible to Complete a Spec-Op under EST time & Solo & Veteran!

Hey everybody look!! We have the best player in the world here gracing us with his
presence! You're cool dude

No it seriously is possible (although that guy sounds like a real winner with a lot of
important thing to do beside mw). I just got the game about a month ago and beat all echo
missions today. Just get good at the thumper headshot.