Stock longbarrels (longshot, long-range kit, rayvan, etc.) can do absolutely nothing but hurt performance. Aftermarket & homemade long tight fitting barrels (brass, sleeper/angel breeches, worker/artifact breech kits, etc.) usually provide a significant boost to performance. This is because all stock blasters only have a short real barrel, usually right around the length fo the dart at ~3", despite also having different plunger volumes. Adding a full breech and long barrel to e.g. a Longshot will instantly boost performance because you can use all that extra plunger volume to propel your dart - volume that was just vented uselessly stock.
Many stock springer blasters benefit from longer barrels - I've got a Tech Target with 5" of CPVC and no other mods that'll hit 80' no problem. Not an exhaustive list, but Longshots, Retaliators, Nightfinders, BBB's, Crossbows, and numerous others benefit from long barrels.
No flywheel blaster benefits from a barrel much longer than the cage.
Pneumatic blasters sometimes need longer barrels to utilize lower pressure/high volume setups - HAMPS likewise need longer barrels. Othertimes they're just like springers except with way more power.
Stringers/direct fire blasters don't have barrels in the traditional sense, they're really more like crossbows.
See the SCAR Barrel (IIRC, a knock-off of JSPB/3dBBQ's barrel but maybe he came second). Jury is out on whether it works or not, but it's sounding legit. Be advised that it sounds, to me, that spin is not needed for the traditional reasons. I think - from reading up on it and from years of reading smart people say it isn't needed - that it works not by spinning the dart; but that in spinning the dart it causes the pressure behind the dart to be equalized and the trajectory gains consistency. That's the theory that makes sense to me anyway.
That's one of our special filters. It pops up from time to time to emphasize - there is no sniping in nerf. At least, not now or without special rules for losers.
The reason is that, assuming all players have access to the same darts and are allowed the same maximum FPS (thus, the same maximum muzzle-energy), having a traditional single-action "loser rifle" puts you at a disadvantage against me with my full-auto +/-60 dart coil-mag mark-12 prototype: I can drop 60 rounds on you while you're fiddling with your bolt-action. Since it usually takes a few shots to get each hit just because of the nature of darts, you'll be out and I'll be hosing down your teamates.
He's right its very good explanation.