After that I started trying to unlock the silencer for the scar but I seriously hate that ****ing weapon. It might as well only have a 3 round clip. I'd rather use the M4 than this POS.
This is the first I have read, or instead likely noticed, of someone absolutely hating the SCAR-H. The only prior negative attribute I remember someone stating about the weapon is the smaller 20 bullet magazine.
The SCAR-H is currently my favorite assault rifle in the game; granted, I have only unlocked up to the M16A4 and have only sparingly used the ACR, F2000, and AK-47 as pickups. I have unlocked every attachment minus the extended magazines and am about 22 kills away from unlocking those; I have found, while trying to get the extended magazines, the FMJ attachment to work quite nicely and probably have surprised a few people with some of the kills I have pulled off with it equipped. I am also about 10 kills away from having 500 kills with it. I do not have a clue where I am with headshots on it though. Even after unlocking the Extended Magazines, the SCAR-H will continue to be in one of my class setups.
The SCAR has superior accuracy and stopping power though. The trick to the SCAR is to fire in short bursts (2 or 3 round bursts) and to generally use it with Scavenger.
Using Scavenger with the SCAR-H is a very good tip and is the part of the setup I use with the weapon. Without Scavenger, it is very easy to exhaust all of the ammunition that it starts with.
The WA2000 is the stand in for the M21 till I unlock it again. I only use the WA in Hardcore with this setup, but the M21 with a Silencer I use in Core all the time.
So do I but I dont like the WA2000. It must cover a third of the screen, it is damn well huge! I cant stand the M21 or the WA, they just arent for me.
I just recently started playing around with the sniper rifles in multiplayer, as it was a class of weapon I had almost completely previously ignored. I tried the snipers out early in MW2 and could not hit anything with them at all. Now that I have some more experience playing the game, I can actually use them.
I started out by trying the Intervention. I found it to be okay, granted that was my first impression of the weapon and the sniper rifle class of weapons. I thought it was terrible on a follow up shot. Though I do not think because of the bolt action, it just seemed very slow to resettle. So next, I moved onto the WA 2000. I mostly like this weapon, except the excruciatingly long switch between it and the secondary weapon equipped. Last up, I tried the Barrett. I quickly killed ten people with this weapon and unlocked the silencer. I equipped the silencer expecting the damage to only fall off slightly and it seems I was completely wrong on that. Continued below . . .
Since we're talking about snipers I put a silencer on my Barret today and its not as bad as I had thought it would be. Its still possible to get one shot kills fairly easily. I haven't tried the WA2000 but I've always thought it was interesting looking at least...
I plan on using the silencer on the Barrett only long enough to unlock the Heartbeat Sensor. After that, it is back to unsilenced and mostly one shot kills.
Now that I have a better feel for using a sniper rifle in the game, I eventually plan on trying the others some more and see if my initial impression of the weapons still hold up.
And yes, it is my favorite. 
I've said this before, but if you can't get that much stopping power + accuracy to work for you, I don't know what the problem might be. M4 is nice. It used to be my favorite until I unlock the ACR, but then it just failed on me. It worked for a long time, but it just quit. Still not sure why. Maybe I just bad bunch of bad connection for that stretch. 
