Pre ban - Post ban?

[towpro]

I am confused.  I understand there was a ban put into affect that lasted 10 years.  This ban listed several pieces that you could have, or not have on an AR.  Then that ban expired.  So why do they still list stuff and pre and post?  If I was to buy an AR lower receiver now (after ban expired) am I limited to what "pieces" I can put on this as I build a complete gun?  I understand that 15" (I think it's 15") or longer barrel makes it a rifle.
Can I use a flash suppressor?  I think I am reading that you also measure the flash suppressor when you measure the barrel, so a 14.5" barrel with the flash suppressor qualifies as a rifle and not a pistol?  If I want to build using a longer barrel, is there any value in registering it as a pistol?

Another question I have is can I buy a A2 lower, and put an A1 upper on it?  I am not looking to build a 100% retro gun, but I do like the long triangle forearm of the A1.  I am not old enough to have served in Vietnam, (draft stopped when I was 15) but I grew up watching it, and always wanted an A1

[AtlLaw]

A lot of questions there.  I'll not try to give my opinion all at once.  FWIW, when the AWB expired, all it's provisions did also.  I don't think the "Pre" and "post" really apply much anymore.  You can do anything you could do before the bill was enacted.

Another question I have is can I buy a A2 lower, and put an A1 upper on it?  I am not looking to build a 100% retro gun, but I do like the long triangle forearm of the A1.  I am not old enough to have served in Vietnam, (draft stopped when I was 15) but I grew up watching it, and always wanted an A1

Me to, I carried the A1 long enough for it to be my favorite combat weapon.  I cobbled together an A1 upper and would use it on my pre-ban Colt lower.  After the sunset, I bought a RRA lower for it.

[Graybeard]

Rifles require a barrel over 16" long not 15". Just to be on the safe side of it most come around 16.25" long.

[towpro]

Me to, I carried the A1 long enough for it to be my favorite combat weapon.  I cobbled together an A1 upper and would use it on my pre-ban Colt lower.  After the sunset, I bought a RRA lower for it.

So was your pre-ban Colt lower an A2 lower?  I have seen pictures of the different models with and without reinforcement castings, etc.  But I do not know if both the A1 and A2 uppers will fit on an A2 lower.

[Badnews Bob]

I would stick with A2 parts if I were you they haven't made any A1 parts for some time so most that you find will be well used.

 A2 and M4 recievers are the same just diffrent barrels and stocks, most AR parts will interchange but I am sure some brands will fit better than others.  Also A2 barrels have a faster twist to shoot the heavier bullets A1s do not.

[towpro]

Thanks everyone.  I picked up his last receiver tonight. 

[45-70.gov]

pre ban   and  post ban  is relevant  in  some states
check   local  laws

your barrel can  be  under  16  but  over  16 counting  the flash hider
but  it  must be  affixed permanently as  described by   ATFE

some  guys here in  Florida  just pay  $200 registration  and  use 7 and 10  inch barrels
again check local laws