This will be my first time getting into the whole tax stamp thing, so I have absolutely no idea what I'm getting into. I figured I'd ask the local guys though

I'm looking to build an SBR with the LMT CQB MRP (damn abbreviations)

Do I need to get all the paperwork taken care of before ordering?  This project will come together over the next couple months probably

And when you do the paperwork needed, does it require a serial number?  Not sure if I want to build another lower or just "debo" my s&w lower yet

Thanks for the help

If you're going to use an existing lower...

1. Decide how you want to register the lower (i.e. individual, Trust, LLC, etc.).
2. Submit the Form 1 and accompanying paperwork to the BATFE.
3. Upon approval, engrave the lower with your Name, City, and State in a conspicuous location.  There are legal requirements for the location, size and depth.
4. Order the SBR upper.

I've SBR'd two lowers and purchased a factory SBR and I would recommend getting a factory rifle, if you can.  It is done on a Form 4 with all the pertinent info coming from the dealer making the paperwork a bit easier.  You also don't have to engrave the lower.  Just buy a factory rifle, sell the upper, and put on your choice of upper.

Whichever route you choose, I wouldn't recommend getting your upper until you've got an approved stamp as you've got a non-SBR AR around and that is bad juju.

Here is what you need to do.

You have to submit a form 1 with the ATF.  Doing this requires you to jump through a few hoops.

1.  You must fill out the Form 1 with all of you information and all of the information of the gun you want to build (serial number of the lower, original manufacturer, etc...)
2.  You must then take the form to your local Chief Law Enforcement Officer in the Juresdiction in which you live and have him sign off on it.  If he refuses to sign, then there are a couple of other routes you must take (i.e. starting a trust or LLC.)
3.  With the signed form you must submit two of each of the following:
    A.  Fingerprint forms taken at your local PD
    B.  photo of you no bigger than 2"x2"
    C.  Another form stating that you are a citizen of this country
4.  Once you are done, you must send the all of the information above and a $200 check to the BATFE for them to run background check on you.  It will take about a month.
5.  While the BATFE has all of your paperwork, you must send your lower receiver off to be engraved with your name, town and state.
6.  Once you have received yor approved form 1 from the ATF and your receiver from your engraver, you may then order the parts that mak it a SBR (inyour case the entire upper assembly) and then you may build your Short barreled Rifle.

Local PD has pretty much been full of assholes anytime I've had to deal with them  (can't completely blame them though, knowing what kind of idiots they have to deal with around here)  so I think I'll go the Trust route.  I have some best buy gift certificates I got back from spending too much money there and using my reward zone card, so I'll be cheap and use those to buy Quicken Willmaker

Pretty sure I'll be getting a suppressor to go along with the SBR.. is there different paperwork for that?  

Quoted: Pretty sure I'll be getting a suppressor to go along with the SBR.. is there different paperwork for that?

Form 4 through your dealer.  Contact Mark at PSI for your suppressor needs.  He is BookHound here on the board.