Offense
Possession/manufacture/sale/etcetc., of undetectable firearm
Aggravated Felony (AF)
AF per 8 USC 1101(a)(43)(E)(ii), referring to 18 USC 922(p).
Crime Involving Moral Turpitude (CIMT)
Arguably not a CIMT because includes simple possession and may not be divisible.
Other Removal Grounds
Deportable firearm offense, presumably not meeting the antique firearms exception.
Advice and Comments
CA PC 17280 defines undetectable firearm the same way as 18 USC 922(p), which is an aggravated felony.
Mandatory Detention: People not admitted to U.S. are subject to MD if they are inadmissible for crimes, and people admitted to the U.S. are subject to MD if they are deportable for certain crimes. See advice on Mandatory Detention.