I read a couple of posts that made it sound as if I could have multiple SBR uppers as long as I have a registered lower.  Can these be used on the registered lower, or can I only use what fits the measurements I put on the application? Thanks. Sorry if this is a stupid question.

www.ar15.com/forums/topic.html?b=6&f=22&t=199905

I was wondering the exact same thing.

as long as you dont have any non-SBR'd AR15's your good.

Quoted: as long as you dont have any non-SBR'd AR15's your good.

so you can only have mutliple SBR uppers, no standard AR-15 uppers?

Quoted: Quoted: as long as you dont have any non-SBR'd AR15's your good. so you can only have mutliple SBR uppers, no standard AR-15 uppers?

I meant as long as you have no Non-SBR AR15 Lowers.

If you have Only one registered M16 lower, and NO semi AR15's you may have as many uppers in whatever length you want.

My SBR is registered as a 9mm. Do I just have to send a letter to the ATF stating I want to have different calibers such as .223? The barrel length for the .223 will be 10.5",  same as the 9mm.

Thanks Tony!  I appreciate the detailed answer, that was exactly what I was looking for - it really helped to clear things up for me.

This goes along with what I understood about running other uppers on your SBR lower. The NFA branch need only be notified of permanent changes to your configuration. And swapping uppers at will does not sound permanent.

Quoted: That means that you can legally own all the NFA and non-NFA uppers and lowers you want, as long as you have at least one non-NFA-length upper for each non-NFA-registered lower you own.

Hmmm.  I'm the last guy to nitpick these scenarios.  My standard answer is don't be a dumba$$ and do something like bring 6 lowers equipped with M-16 components, and ONE DIAS, out to the range; stuff like that.  But for the sake of argument, let's say "Henry" owns a RDIAS.  Henry quickly decided that semi-auto sucks, so he sold off all his AR-15 stuff.  He then goes out and buys 6 stripped lowers, several shorty barrels, some in 5.56, some 9mm, etc.  There's ONE set of M-16 components, and when installed in a lower, that's where his DIAS resides.

My point is, it is very possible to have an almost unlimited number of components on hand.  They simply must be assembled with wisdom and above all common sense.  

I have a Colt RR and 15 uppers.  The lower was in A1 configuration when I purchased it.  My Form 4 listed the RR in A1 configuration.  I went to the Indiana State Sub Machinegun Championships in June.  I had made no perminate changes to the lower.  But I was going to use a six position stock, which is A2 length, and a 10.5" 9mm upper.  I called my NFA Branch examiner and asked about travel paperwork to IN.  He suggested that I send the NFA Branch a listing of all my different uppers by caliber and length.  They also wanted an overall length with the stock extended.  So If I got stopped and I have my 6.5" 22lr upper on my RR, a call can confirm that I have this configuration in the data base.

Gorilla, in the senario above Henry only has one machinegun.  It is my understanding that an AR lower receiver is either a rifle or pistol.  Henry will be fine if all the lowers are set up as pistols.  If there is one lower with a stock, then as Tony said, that lower has to have a 16" upper or be registered as an SBR without the sear installed.  The fire control parts are for machinegun status.  A stripped lower is a firearm even without any parts installed.

Having a rifle lower and only short barrels reguardless of firecontrol could bring a charge of unregistered SBR.  With the cost of a Lawyer in Federal Court, even if there was no conviction, it would end up costing thousands of dollars.  That is nothing I would want to risk.

Scott