Can you put a 14.5" barrel on a Colt factory SBR, even though the Form 4 specifically says it has a 11.5" barrel?

I have another lower that I filed a Form 1 on and my barrel length was listed as 10.5"-16", so I'm good to go there. But, is there a LEGAL reason why I cannot put a longer barrel on a gun that is registered as having a 11.5"?

I know, I know...stupid questions for stupid laws.

The form is simply a snapshot of the configuration of the gun the moment it was built.

You can put any barrel length on there.  Putting a >16" barrel on there even removes the weapon from the purview of the NFA while it's in that configuration (IE you could take it to non-NFA states, could travel interstate without a .20 as long as you didn't have the parts with you to return it to NFA configuration).

Just FYI: the ATF no longer accepts a range of lengths or "multi" in the caliber or length sections.  That doesn't fit the use of the form.

So you're saying that since you have a non-sbr upper on the sbr lower, it's going to be treated as a standard rifle and no permission to travel form (I forgot what the form was 55xx/53xx or something like that) is required to leave your home state? Is this really true?

SBR's are classified in totality. (Source: Answer one http://www.atf.gov/firearms/faq/national-firearms-act-short-barreled-rifles-shotguns.html

Yes, there is no .20 needed if you don't retain control over the SBR upper - IE you leave it at home and don't bring it across state lines with you.  (Source: Answer six http://www.atf.gov/firearms/faq/national-firearms-act-short-barreled-rifles-shotguns.html)

Thanks for the link.

It is my understanding that as long as you can return it to the configuration specified on the form1/4 you are good to go

If you are going to make a permanent change " They" need to know.

I'm enjoying a 10.5" PWS pistol build waiting on a Form 1

The ATF requests (but does not and cannot require) that you notify them of any permanent change.

Also only partially correct. There is no "need" to notify them of a change. They request that you do, but it is not a legal requirement. Besides that, the AR15 is such a modular platform that nothing can be really called a permanent modification.



You don't have to retain the original upper with the barrel length specified on your form. That is a myth.



Also, you will enjoy your MK110 as a rifle. My MK110 SBR just approved today. It's going to be even MORE fun now that I can legally go bust that bastard out of jail instead of just conjugal visits. ;)