Yep, that's pretty much the complaint that everyone has had with the recon class. In Bad Company 2 it was a bit more powerful as a class and it was much better because you didn't have scope sway or scope glint like you do in BF3. Some people complained so hard about the recon class that DICE nerfed it beyond belief. Using sniper rifles is very unrewarding in this game.
I'm sure you knew where it was best to get a hit but I wanted to stress it because it's the only way you'll do okay with these guns. If you are not really getting any kills and you're hitting them then you aren't getting that headshot.
The M98b is best for long range since the bullet travels faster than any other gun. That being said, you'd do much better running the SKS or M417 sniper rifles with a Kobra or Red Dot sight and getting in closer. You'll land more shots and even though you lose the chance of getting one hit kills since they are semi auto, you can still fire more shots at a guy and do a lot better.
Also, I like the 870 a lot too. The SPAS 12 is great as well so try seeing which you like best. 870 fires 2 more pellets and does more damage but the SPAS fires much faster. I'd actually say the 870 is much more reliable for one shot kills as long as you get a square shot. The SPAS isn't as reliable since you'll get kills from a mile away sometimes and then outright fail at point plank another time.
Wait until you get slugs though.
