what's this "sniper barrel"? what brand is it?
the onyl thing you can do now to make it more accurate is to buy paint that matches your barrel bore. you can find charts here
http://www.pbnation.com/showthread.php?t=916326
I'm skeptical that it works, but it's worth a shot If anything, you get better efficiency out of it.
Teh general idea is to get paint that's a few 1/100 of an inch smaller than the barrel. Or you can buy a barrel kit, buy whatever paint you want, and match it when you go play by using whatever size barrel back works.