The 2k is a popular Nerf blaster from 2002. People like to take the tank out to integrate into other things because it's small and can hit 100'. Most people don't keep the original 2k shell, specifically the turret.
The reason is that the 2k turret is so masterfully designed by Nerf, there is almost zero error margin for re-barreling. Some people do still rebarrel their turret, but making the turret rearloading is stupidly complex. I decided that it couldn't be anywhere near as difficult as people claimed and set out to make my own rearloading 2k.
The hardest part of making a rearloading 2k is making sure all the barrels seal without ruining the rotation mech, a feat that I accomplished. However, it also requires the extra space to be filled, and I used hot glue. Which was stupid, but I wanted my 2k. So no perfect seals for the barrels. They do, however, seal well enough.
With a plugged pump and 12" PETG barrels, the 2k hits consistent 90's with slugs. With good domes, it could probably hit 100's. It does rearload, but the 2k is so small that it's usually faster just to muzzle load each barrel.
All in all it's a cool primary, but making it rearloading is more of a status symbol than anything else. It is however, the smallest primary I own, so it will probably come with me should I ever travel cross-country for a Nerf war.