So I have just placed a order for the CMT Monolithic Lower with PDW Stock and will build it into a SBR. I have a few questions about the process as I have never purchased/built a NFA firearm before.

First of all I am going the gun trust method. OK in Colorado.

1) Do I need to have the lower in hand to file the form 1. - I know I need to submit the dimensions on the form 1 , do I need to know the original serial number the factory assigned to the lower? Or will I only be asked for the "new" serial number I assign to the lower with the name of my trust.

- I am asking these questions because I purchased the lower on layaway. Since it will be a while before I get the tax stamp I am trying to determine what the most efficient use of my money is.   Ultimately I would like to set up the trust and file for the tax stamp before I am in physical possession of the lower. Is this possible?

2) Is it true that once I get the stamp: Lower is registered as a SBR,  I am able to change the configuration from the specifications it was registered originally?  To explain, for example on my form 1 the SBR is registered with a 10" 5.56 upper.  Six months later I get a 8" 300blk Upper and attach it to my SBR lower, is that legal to do?  To change the configuration to a shorter barrel in a different caliber?  Would I need to hold on to the upper I used when I originally registered the SBR,  or would I be allowed to sell it?

CMT makes some awesome products.

1) you will need the serial number that cmt puts on the lower along with the model number they stamp on it. On a side note CMT did an awesome job engraving my SBR from them. You might want to look into getting it engraved before you pick it up.
2) once you have the stamp you can change the configuration including caliber to your hearts desire. And no you don't have to keep the original upper.

Instruction 2i of the Form 1 tells you to use the original manufacturer serial number if an existing firearm is being modified into an NFA weapon.  I don't think you necessarily need to have it in your possession  file, but you do need the serial number (and if you're buying a gun on lay-away, the serial should be on your receipt).

I encourage you to download a blank Form 1 and read all the included instructions.

thanks for the help guys.  I am sure I will have a few more questions as the process moves along.

Thanks for the tips guys.  I reviewed a form 1.  The thing that is slightly confusing to me is:



Question: Even thought I am assembling the rifle from parts, the lower qualifies as an "existing firearm" ?  And thus I use the serial number supplied by the original manufacturer of the lower?


The second question I have is, due to the fact that I am registering the SBR to a trust.  I will need to engrave the: Name of my trust, City, and State on the firearm (lower).  I dont know if I have overlooked this, but I dont see any rules stating that I must do so on the form 1.  Is that Information in a different form?  What am I missing?  
(I read the from 1 off my phone so its possible I overlooked it, in which case I apologize for the oversight.

Thanks for your help and patience.

The requirement to engrave the maker's information (and you're applying for permission to make an NFA firearm) is nor found on the Form 1, but in the ATF regulations, specifically 27 CFR 479.102.  You'll need to engrave the name of the trust, and the city and state where it was (will be) assembled.