Like the T-102 Jagdfaust & Gebirgskanone, it is better treated as a high power assault rifle than a weapon to take out massive hordes in a single blast. It shoots fast moving red plasma bolts that deal Energy damage to enemies that go near them & explode on impact. The blast radius is rather small for a rocket launcher along with very low pierce but zombies are usually close together so the pierce is somewhat mitigated by rocket launcher mastery and its decent RoF.
The HIKS 3100 is a great weapon to fight bosses and works well with Shielders because it can damage them from the front. Overall the HIKS 3100 is a great weapon. When modded properly, it can become an extremely powerful weapon, capable of dealing over 2,000 damage a shot with high damage ammo for the basic version, or over 6,000 damage a shot with the version. This weapon is a must have if found with high augment spots. It is useful in backing up bounty points & making events like apocalypse much easier. This weapon strikes a fine balance between the assault rifle class weapons, with its higher RoF when Overclocked is added, & a rocket launcher. This makes any one with this weapon a major power house in battle.
Piercing & Enlarged are typically not useful, as the base explosion is too small to be worth upgrading. Pinpoint can make this weapon excel at killing bosses due to the high base damage coupling with a critical damage boost, but augmenting Pinpoint is not recommended unless your character has sufficient points in Critical Shot & Target Assist on the helmet. However keep in mind that the only bosses with Energy Resistance are the Necrosis, Wicker & Loaderbot.
The HIKS 3100 has few, but heavy downsides. It weighs more than all Non- RLs. Being an Energy Rocket launcher it has the highest ammo cost. It also has low pierce & blast radius. It has a somewhat lengthy reload, & is relatively rare until later levels. However, if you find a good one, it is very much worth keeping.
A previous update has caused the base movement penalty to display incorrectly if it is augmented with Skeletonized. Rather than always displaying a base movement penalty of 50%, with the penalty reduction from Skeletonized after it, it will display what the base penalty is with Skeletonized factored in. A HIKS 3100 without Skeletonized augmented on it can be seen here, & one with Skeletonized augmented on (& the resulting bug included) can be seen here.
The HIKS 3100 received a "Easter Edition" around Easter (March 28th) 2016. It was called the Nerves of steel [sic], & replaced the HIKS 3100 from strongboxes & crafting. Its description was "Real annoying, real grumpy, and REALLY full of himself". This also happens in Easter 2017.
The version of the HIKS 3100 on the PC only has red stripe-like design but the mobile version has more red paint covering the gun.