Fired with Fireball "premium" paint (from Draxxus, Exotic Sportz, used at Hell Survivors playing field)
Accurate, light, sturdy, easy to clean barrel, inexpensive
Porting not easy to clean, longer than average barrel
I played at Hell Survivor's infamous Monster Game over the weekend (a grueling 12 hours of playtime), and was genuinly shocked at the Smartparts 14" Linear barrel's performance. I paid a scant $12 for the barrel, and "you get what you pay for" did not apply. Normally $35, eBay was able to save me almost three times the cost of this barrel.
During the course of the two days, I made several confirmed kills with laser point accuracy. The stock barrel is simply too inconsistent in its shots, leading to many dips and curves of the balls over range. The Flatline, although handy for getting that extra range, suffers the same dip-and-curve problem over range as the stock barrel. I was slightly more pleased with the Lapco 14" barrel I have, but again, over range, I was placing shots in a 6'x'6' square--great for an aftermarket barrel. When I screwed in my Linear this year, I was blown away. At 100', I was putting 90% of balls in a 3'x3' square. The accuracy was phenomenal. I lose the range advantage of the Flatline, but the accuracy more than makes up for it. I don't tend to long-ball the opponents, and prefer to be a little more up close where I can guarantee ball breaks.
The laser-accuracy of the barrel undermined by the incosistency of CO2. My next upgrades will be to an HPA system. Hopefully, it'll keep my velocity more consistent and result in fewer dropped balls.
The Linear barrel was also quite durable. I routinely threw the barrel down onto cover, using the cover as a hardpoint mount for the barrel. I didn't see any chips or cracks in the barrel after 12 hours of playing and beating up my barrel. The only time I had a ball break in my gun was when I slipped in mud, shoved the barrel into the ground, and came up with an inch of mud caked into the barrel. I fired a couple of times to clear the crap out (never do that with a real gun, eh), and noticed I had a ball break in the barrel. Nothing a little wiping didn't clean out.
The greatest downside of this barrel was that I kept pushing into objects (on accident). I'm used to the rather short 8" stock barrel and Flatline, so running around from cover to cover left me poking my gun into plywood, trees, and other hard objects. A testament to the durability of the A5 and Smartparts barrel, to be sure.
I'm a cheap guy, and I wouldn't have bought this barrel at $35. Getting it at so low cost genuinely surprised me. If you see $35 lying around and you don't have an excellent barrel, this is definitely a great one to pick up (they come in 14 and 16 inch flavors). For its low cost, the performance advantage is huge over stock parts.