GOOD THREAD. I'll tell you a true story. Guy gets a lower and wants it to look cool. That means collapsible stock. Oh and it had to have a shiny chrome bolt. Now for the upper. Hmm the standard 20" barrel is too plain. The 16" is nice... ooh look, a 10.5"! Awesome!! I guess I better get the 6" flash hider to stay legal I suppose... let me call the gun shop in AZ..."Hello? I wanna order a 10.5" barrel, do I need to buy the 6" flash hider? Oh you will sell me the standard birdcage flash hider? Yay! Ship it to me in CA." Wow I can't wait to have a cool gun!
And he gets the parts.
And his newly home built SBR is indeed way cool looking.
And the cops see it at a shooting range.
And he loses it.
And all his other guns.
Don't trust what gun stores will sell you, they do not care about the law and are not responsible for keeping you within the law. They sell stuff is all. If you do not know the law, do not guess. And since this is CA, if it is cool you better double check its legality.
"If Jesus had a gun he would be alive today"-Homer Simpson