Kroot weapons are a type of Autogun/Stubber/we don't really know cause the difference between Autoguns and Stubbers are so convoluted thanks to GW incompetence. Basically more shitty versions of Imperial projectile weapons that is still used thanks to the saving grace of Tau munition upgrades. Kroot weapons have thus, earn some sort of niche within the Tau's armory. Although this can be said due to Kroot stubbornness to change to a better weapon more than anything else.
They are also the only chaps that still uses bow weapons in the 41st millennium. Figures.
The Kroot Rifle is the basic weapon used by the Kroot. It works by firing a solid slug propelled by a chemical reaction, although it was adapted by the Tau to fire Pulse rounds to make it the equivalent to the Boltgun.
It is armed with blades near the muzzle and stock and are a throwback to earlier Kroot Fighting Staves, allowing them to use their speed to tear close in on their opponents in close combat. It is still quite bulky however, and so is not ever combined with another weapon, although it doesn't often need to be.
In 8th Edition, the Kroot Rifle is a relatively mid-ranged 24" weapon. However, it is an Rapid Fire 1 gun that is S4, AP0 and deals 1 damage per gun. It should be enough to deal with GEQs, however, it would struggle against MEQs. What is unique about this weapon is that ALL Kroot Rifles are also adept melee weapons as well. On a charge or in CQC, the Rifle is a S+1 (So a S4 weapon), AP0, D1 hatchet. So in a group, these guns become quite dangerous if the dice gods are in your favour.
Other versions of the Kroot Rifle are the Kroot gun and Kroot hunting rifle as seen below.
Kroot Hunting Rifle
The sniper rifle of the Kroots.
The Kroot Hunting Rifle is an adapted form of the basic Kroot rifle for those Kroots who like to snipe their prey at range and not get their hands too dirty. This version is customized so it is more adept for hunting, meaning it is quieter and has a longer range. These properties make it favorable as a Sniper Rifle to the Kroot.
Kroot Hunting Rifles loses their bayonets more commonly associated with the more common Kroot rifle. This is for obvious reasons such as having more stability and not too barrel heavy which will affect the accuracy of the gun.
It bares resemblance to the Imperium's Stub Rifle in a lot of ways.
Unfortunately, there is not actual crunch for this weapon on the tabletop as it appears only in the trading card game and in a few models.
The Autocannon of the Kroot weapons.
The Kroot Gun is a weapon used by Kroot mercenaries. It is a heavy weapon strapped to the back of a Krootox. It is effectively a larger version of the Kroot rifle. It is so big that it cannot be wielded by hand.
The Krootox and the gun are often incorporated into Kroot Carnivore Squads made up of Kroot, Kroot Hounds, and the aforementioned Krootox. Because of its high strength, the Kroot gun is usually utilized to protect the squad it is in from attack by units within transports and heavier vehicles.
A twin-linked version of the weapon exists, and is toted on the backs of a Great Knarloc. Obviously it functions identically, but with the caveat of having double the barrels, so double the firepower.
In 8th Edition, these guns are 48" Rapid Fire 1 weapons that are S7 Ap-1 D3d. Good enough to pluck off the occasional MEQs, but not good enough to deal with armoured vehicles of TEQs unlike the Autocannon. Rather, the gun is used in conjunction with the Krootox's natural strength, softening up the opposition before going in close. As such, use this more like a secondary weapon than a primary one.