yeah, they can be very accurate. .20s would explain why, you should at least use .30s, maybe even more, who knows?
And also if you want a very good sniper rifle be prepared to spend a lot of money on upgrades. A mate got a VSR, (known to be the best sniper rifle platform) and was only happy with it accuracy and range wise once he had spent close to £700 on it. And even with an sr-25, be prepared for gb upgrades, tbb, mosfets, batteries, all sort of things