title says it all. this is my first firearm so this is all new to me. registration is mandatory in hawaii right? anything else i should know? i was going down to hpd tomorrow so let me know.

Yes you can. Just bring the lower

They will ask you when you complete the rifle to bring it back so they can list the barrel length and caliber.

BUT it is NOT mandatory.

If the AWB was to pass and you only listed the lower... then only the lower would be grandfathered in and not the full rifle. and if you were to complete the rifle at a later date and the "said awb" does pass then you are stuck with just a lower and if you attached a upper even though you already owned it you would be in violation of the law to my ignorant knowledge.( IF upper had a fore grip or bayonet lug or any other accessory listed in the bill now rumored amendment....

that is if the awb will be reintroduced

I brought just the lower in once cause I was refinishing the upper and they registered it just as a lower.....

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So what do you do if you have one lower and three uppers? 

My lower was registered as just a lower as well. My train of thought is piss on them, I could mix and match without breaking any laws provided the upper isn't an SBR. They didn't tell me to come back or anything.

If the AWB was to pass and you only listed the lower... then only the lower would be grandfathered in and not the full rifle. and if you were to complete the rifle at a later date and the "said awb" does pass then you are stuck with just a lower and if you attached a upper even though you already owned it you would be in violation of the law to my ignorant knowledge.( IF upper had a fore grip or bayonet lug or any other accessory listed in the bill now rumored amendment....

damn. good point. didnt think of that. maybe i should bring the rifle then. hmmm,  thing is i was getting dropped off and may need to catch the bus. i guess i could register the lower and bring the rifle another day. i mean its not like the cut off date for grandfathered weapons will be anytime in the near future IF that AWB even passes right???

They told me bring the one you use most.

Stupid just stupid......

Just wondering how it's known to not be mandatory?  Did they say so or something?  I know they write like "receiver only" on the registration.

Basically, they wanna know what they are up against if they come a knocking... CONTROL

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If the AWB was to pass and you only listed the lower... then only the lower would be grandfathered in and not the full rifle. and if you were to complete the rifle at a later date and the "said awb" does pass then you are stuck with just a lower and if you attached a upper even though you already owned it you would be in violation of the law to my ignorant knowledge.( IF upper had a fore grip or bayonet lug or any other accessory listed in the bill now rumored amendment....

  But as someone posted above if their were an awb and it was just the lower registered, then you may be stuck with just the lower.  Someone correct me if I'm wrong

Where are you guys getting this info. from. All my ARs were built from lower up and as such, all were registered as lower receiver only.

Registration doesn't say anything about collapsible stock, pistol grip, bayonet lug, flashhider or any of the "evil" cosmetic features of an upper or lower. Just make, serial no. and barrel length.

I would think so long as you don't mount an SBR you should be good to go as far as grandfathering.

Then again, I'm totally ignorant on the subject.  This might be HUGE for all the folks here who registered lower receiver only.

Could I take 3 lower receivers and 1 upper and just keep popping off the same upper, remounting it to the next lower and passing it through the window again ? 

^^^You could, but there is no point to mounting and remounting.  Just register as a multi-caliber lower.