Optimum performance

Barrel length should not be longer then 14" and any size HPA tank still puts out the same pressure...

Barrel length doesn't really matter past about 8".  Just note that anything over about 16" and you start to waste air trying to get the paintball to the same velocity as a shorter barrel.

As for an HPA tank, the A5 requires high pressure output (the standard for these tanks is 850 psi).  The vast majority of HPA tanks that are out today are high pressure output.  Other than output pressure, nothing on a tank will directly influence the performance of your A5.  Its just picking a material, size, and company.

It will cost a little more, but I highly suggest a fiber-wrapped tank.  Steel tanks start weighing a lot past 48/50 cubic inches, and a tank like that will only last you for about >500 shots.  As for size, 68 c.i. / 4500 psi is pretty standard on a general use marker such as yours.  It will provide plenty of shots and will in most cases last you for quite a few games.  As for companies, my opinion is that Crossfire and Custom Products make some of the most consistent regulators in the industry today.  Its not a huge deal on something like an A5, but it does make a small difference.

Rambino wrote: Yomillio wrote: Barrel length doesn't really matter past about 8".  I'm not sure I would agree with that.  A friend of mine has an 8" Bigshot, and I have a 12" Bigshot, both on our A-5s.  He loses accuracy at range noticably before I do.  He also sees accuracy improvements at range when he puts on a longer barrel. Obviously not a large sample, but it does seem to me that 8" may be short of the optimal accuracy length for barrels - at least for Tippmanns. That said, I agree that long barrels (>14") serve no purpose other than cosmetic, unless you are playing airball.

Yeah, its quite debated.  Some say yea, some say nae.  Get a 12-14" and be happy.