Secondary Kitguns were originally released in Fortuna in U24. As the playerbase began to experiment with them, much like with Zaws on release, we found them to be generally top-tier, or even best-in-class for the most part. Some time later in U28, we were given the ability to create Primary Kitguns as well. They use the same Chambers and Loaders as Secondary Kitguns, but with new Grips. These new Grips largely correspond stat-wise to the existing Secondary Grips.
The Tremor has the highest Damage/lowest Fire Rate, Steadyslam increased Damage/low Fire Rate, Shrewd reduced Damage/higher Fire Rate, and Brash lowest Damage, highest Fire Rate. In the case of the Gaze beam weapon, Fire Rate is constant, and Grips affect Beam Range instead.
Like when the Secondary Kitguns came out, I'll be going through each Chamber, how it compares to what is already out there, and how I personally would recommend building it. Unfortunately, Semlar's Kitgun builder has not yet been updated for Primaries, however the Wiki page does have a full table of all the builds. Again, all stats will be based off of Gilded version, which consume 5000 Fortuna standing and 10 Shelter Bonds.