So I submitted a form for a Spike's tactical which was simple, the lower receiver had a simple, all numeric serial number.

I am also converting a S&W M&p-15 AR to SBR and I was wondering what tyo use for the serial number.

The serial on the AR appears to be "SVxxxxx" (the Xs are numbers).

Do I include the SV in front of the numbers?

Yes.

Definitely. Some serial numbers have letters in them, it's perfectly normal.

Thank you for the responses! Good to know. All the other lowers I've done haven't had letters. I guess Smith has them because they are larger and higher volume.

Indeed and this is a fairly common question and an even more common reason why forms get rejected by the ATF...someone posted about it on Reddit's NFA forum a few months ago.

And while we're on the subject of serial numbers...

A little over a year ago I bought two sequentially numbered Spikes Tactical lowers...the serial numbers started with SBRXXXXX. I considered it a sign from the NFA gods and turned them both into SBRs (my first SBRs, for that matter!).

Word around the campfire is that Spikes planned to make their own run of factory SBRs and then Newtown happened and they just sold the lowers as-is in an effort to get more product out the door during the ensuing panic. When asked, their official response has been that the SBR prefix in the serial number stands for "Spikes Battle Rifle."

While researching it, I saw one on AR15.com for $$$$$$$ because of the "special" serial number...I don't think anyone jumped on it. ;)

I have a similar question about a lower I e-filed last month - it's an Area 53 and on the receiver it has a SN:XXXXXXX. I did not included the SN: simply because I assumed the SN: wasn't a part of the serial number itself because of the colon. Hopefully I didnt screw this up

You should be fine. SN: would mean "Serial Number:" If you have the receipt from when you bought it, it should show the serial number.