I have a preban AR with a 20 inch upper on it. I want to change it to a 16 inch barrel and I wanted to also buy a 14.5 in barrel for it. Now the question that I have is that if I file for a SBR tax stamp, do I have to purchase an AR with the 14.5 in barrel or can I just buy the 14.5in barrel and put it in my current AR once approved for the SBR? Any info will help..

It would be better to simply have a FS fixed to the end to bring the total length up to 16". A lot less paperwork that way.

The lower is the portion of the rifle that is registered as an SBR.  Once it is approved and you have your stamp for it you can put any length upper you want on it.  I too am in the process of filling out the paper work for an SBR.  I'm going to make a 11.5" Commando clone.

For those of you that are wondering, I have not purchased the 14.5in upper yet. I did not want to spend the money on it or worry about violating the law until I had my question answered. Thanks for all the information.

my opinion it's a waste of money to pay 200 dollars and going through the paperwork just to have a barrel 1.5 inches shorter. a 14.5 inch barrel isn't going to look that much different then one that is 16 inches.

doing a SBR for something that has a really short barrel is one thing, but for something that will be just be 1.5 inch shorter? I don't believe it's worth the paperwork and money

now I can see a SBR being done for a AKS74U.

Yes, but remember once you have the stamp you can attach ANY length upper to the lower rec.  So if you get tired of the 14.5, get a 10.5, or 11.5 or whatever...heck go back to 20" and down again!  Then with any of those lengths you can reg. a can and mount it to a 14.5 or whatever since you won't have the perm. attached FS.

Lots of variations with a reg. SBR=fun!

I don't know about that, on the form 1 it states what length the barrel is....if you put 14.5 inch, and then put on a different length (under the 16 inch) like 10 inch.....technically I believe it wouldn't be legal. as the tax was paid for a 14.5 length.......the length on the approved form,  won't be the same length on the gun........in any event I wouldn't want to be the legal test case for it.

taking somebody's post that it is OK to do, on a dissusion board,  is not my idea of sound legal advice....and please, don't take this the wrong way, but there are just too many shit house lawyeres on these boards, that think they know everything about gun laws...some of them think they wrote the laws.  

To fscrt does that mean you have to pay a$200 dollar tax on every barrel legnth 14.5 to 10"?if so that maks buying a newupper $700 per upper,that would be too much hassle and money,but if I had the dough id probably do it and have true legnth variants to mimic the real ones.

You are registering the lower (it is the firearm/serial #) as the SBR. SBR is allowed to have "a barrel shorter than 16 inch"... You do not need to register each barrel. I have 1 SBR AR-15, and 3 working uppers currently, in 2 calibers.

OK i'll give you that a SBR is any barrel length under 16 inches.....but just because the upper is easily swapped out, compared to other weapons where the barrel can't, how does that make it legal to have the paperwork say one thing, and the rifle another? I understand that the serial number will be the same....but the length and caliber won't jive with the paperwork.

can you cite a ATF reg that states this is legal?

the reason I ask, I don't think they put a block on the form 1 that states what the barrel length, and caliber is,  just for shits and giggles. if the serial number is registed to have a certain barrel length and for a certain caliber....I don't believe they will allow a varance for another length or caliber on the same form. but I could be wrong.....if you can prove without a shadow of a doubt, that this swapping out different lengths and calibers is legal, despite what the paperwork for that serial number is,  then I will bow to your knowledge.