Must be 16" overall length barrel, either 16" or a shorter one with a pinned and welded muzzle device that brings the oal to 16".
Cali doesn't care about bayonets.
If you go featureless, you will need a muzzle device that is non flash supressing.
Assumption is the mother of all ****ups.
Know what you know, Know what you don't know. -Paul Pedzolt
"Jack of all trades, master of none, though oftentimes better than master of one" -Mynshul