Q:

Do Kaigins get grit?

Psionic Deed
At 2nd level, the kaigun gains access to a single 1st-level deed normally available to a gunslinger. This deed works and interacts with grit the same way as gunslinger deeds. If the kaigun also has levels in gunslinger, he can spend grit points from that class to use this deed.
This ability replaces Evade Arrows (+1).
Editor’s Note: In addition to the standard deeds available to gunslingers, kaiguns and other characters with access to deeds and the psionic subtype have access to a special class of deeds called psionic deeds. A complete list of psionic deeds can be found here: Psionic Deeds.
How do Kaiguns then used this deed if they got no grit so start with?

A:

They earn grit.
Kaigun:

Gun Wielder
At 1st level, the kaigun gains the Amateur Gunslinger feat and the Gunsmithing feat as bonus feats. He also gains a battered gun identical to the one gained by the gunslinger.
This ability replaces Point-Blank Shot.

And...

Amateur Gunslinger
Benefit: You gain a small amount of grit and the ability to perform a single 1st-level deed from the gunslinger deed class feature.
At the start of the day, you gain 1 grit point, though throughout the day you can gain grit points up to a maximum of your Wisdom modifier (minimum 1).
You can regain grit using the rules for the gunslinger’s grit class feature. You can spend this grit to perform the 1st-level deed you chose upon taking this feat, and any other deed you have gained through feats or magic items.

