nice, i'm new to upgrading guns, have you done any other mods to your barretts? and upgrades you would reccomend?
no worries, I'm personally of the opinion "if it ain't broke, don't fix it",unless there is something actually wrong with it, or you've got a specific thing in mind I'd just clean the barrel and play with it until it dies.
in terms of things I've done, the carbine one has the most rounds through it, and the upgrades are:
13:1 gears from AK2M4 (SHS if I remember correctly), changed the old ones as I went through a ROF period, added maybe 3-4rps.
Lonex red piston (stripped the old one after about 15-20 games) recommend airlab as the better supplier.
at the same time as the above, I put on a POM mushroom silent head (can't remember the make)
firefly hard hop rubber (only put this in if you've got everything else right, should add a few metres).
and as an additional, they use the crappy green lube/gunk in the boxes, I would recommend getting rid of it as soon as possible. probably the only thing I would recommend to be done immediately. there are a couple of other things I have done because of the external modifications, so I won't list them.
when you do upgrade, do one thing at a time, much easier to trouble-shoot.
any problems, give me a buzz