Section 17270 Of Division 2. Definitions From California Penal Code >> Division 2. >> Title 1. >> Part 6.

. As used in this part, an "unconventional pistol" means a firearm with both of the following characteristics:
  (a) It does not have a rifled bore.
  (b) It has a barrel or barrels of less than 18 inches in length or has an overall length of less than 26 inches.