yep, All those barrels that bigred mentioned are great and the size of the barrel is all just personal preference, i prefer 12" since any longer it's usually just a hassle ... but anything shorter ... is not good
... but it's really all up to you
You could also probably change to HPA for a consistency of shots, thus allowing your paintballs to travel straighter...
Besides that if you want you can convert to a LP system which would be a bit of money ...