I see them advertized as 12.5". However I measured mine and it came to end of chamber to end of muzzle 11.5"?  What is yours?

Yep. Same here.

I have the most recent Century catalogues and they say the barrel is 12.25". My tape measure says the two I have are both 11.5".

Yup, mine too. The stickied Draco spec thread has 12.25", maybe we should add that empirical data shows 11.5".

Hmm... I'm going to go measure mine now. I always thought it was 12.5".

The AMD 65 is 12.5".

Sure enough, just went and measured mine and it's exactly 11.5".

Shit, how anal is the ATF? I sent out my SBR paperwork claiming it had a 12.5" barrel. Will they even give a crap? Just makes me worry a little since I'm so detail-oriented when it comes to legal forms like that...

I would send the ATF a letter stating exactly what happened and letting them know that your answer to 1e on your Form 1 was 12.5" and should read 11.5".  

After owning an M16 for 14 years I NEVER heard from the ATF, neither has anyone I know and that is a lot of NFA owners.

Why would they even bother measuring a barrel on an SBR?

Yep I was filling out the form 1 and got to the BBL length and thought I better get this right. Hmmm 11.5" Nice!

mines 11.75

To each his own. Following your logic, why bother measuring in the first place when you fill out your Form 1? Just take a guess and who cares because the ATF is never going to measure the barrel of an SBR.... You may be right, but you may be wrong. The best reason I can give why he should contact the atf about this is because he has posted in here that he is aware the information put on his original Form 1 was inaccurate. The fact that you and your friends have not heard from the atf in many years and you own a machine gun or two does not address the issue. I assume you and your friends all submitted correct paperwork so you are not in the same position as this guy. He says he is detail oriented about his legal forms, so I say he should send a letter or otherwise correct his Form 1. Why risk it...

Everybody swaps uppers on their M16s, rendering the barrel length on their Form3/4 inaccurate.

So when police depts get M16s on Form 10s and trade off the A1 uppers for new M4 uppers do you think they inform the ATF?  I don't