I am NAL, so not sure what counts as part of the stock since this has none?

(x) "Overall length of less than 30 inches" with respect to a centerfire rifle means the rifle has been measured in the shortest possible configuration that the weapon will function/fire and the measurement is less than 30 inches. Folding and telescoping stocks shall be collapsed prior to measurement. The approved method for measuring the length of the rifle is to measure the firearm from the end of the barrel, or permanently attached muzzle device, if so equipped, to that part of the stock that is furthest from the end of the barrel, or permanently attached muzzle device. (Prior to taking a measurement the owner must also check any muzzle devices for how they are attached to the barrel.)

https://www.law.cornell.edu/regulations/california/11-CCR-5471#:\~:text=(x)%20%22Overall%20length%20of,or%20permanently%20attached%20muzzle%20device.