There's a gun in every weapon class every COD that is OP according to someone within the community. Personally, I didn't think the Bulldog was that great - unless you were in CQC.
I got into a really ugly debate with someone back during MW3 regarding the SGs in that game. I have some video of me somewhere getting a MOAB using an AA-12. That SG was supposed to be too weak to use.
It took me a while to figure out that everything in every COD ... works. But I figured it out during the WaW season by going back and "finishing" COD4: MW. I never did prestige in that game - there was literally no reason to do so. However, while I was waiting to have heart surgery, I went and completed every single challenge in the game. By the time I got ... I'd say about 70% to 75% of them completed, I started realizing that, "Hey, these guns are not under-powered or over-powered." You just had to find where they worked best. Same with the perks. Remember Eavesdrop? That absolutely had to be the most useless perk ever in COD.
Yet, today it is one of the most relied upon perks in the game. Sorta. Granted, in MW we could hear "nearby" enemies (who happened to be using a mic - which was practically no one) at "all" times, the reality was that you rarely heard anyone and when you did, it was as you were killing them. That's a lot like the kill mic that we've had for a few titles in a row now.
But Eavesdrop worked when you had to go up against a party / clan. In fact, it could be a funny perk to use for those times. But ... it required you to go 100% stealth, silencers and Dead Silent.
Weapons that seem "too weak?" You really have use Overkill and keep them as a secondary. I guess it depends on how you look at things. True, even if you run OK, a weak gun is still a weak gun. But scoring kills is not what I find fun. Meh, you can always use the easiest weapons in the game and score a lot of kills.
But when you can run a 15, 20, 25 kill streak and kills 25% to 50% of those kills using the "weakest" gun in the game???
I'll be honest with you ... that is the one thing that has always made COD fun for me more than all else.