[servo1969]

Here's the original 11-26-2012 letter from the ATF stating that putting a SB15 Brace on an AR pistol does NOT make it a rifle:
http://www.sigsauer.com/upFiles/ATF-Compliant-Letter.pdf

Here's the new 3-5-2014 letter from the ATF Technical Branch stating that shouldering an AR pistol with an SB15 Brace does NOT make it a rifle:
http://www.scribd.com/doc/216207869/SIG-BATFE-LETTER

Also- manufacturers are starting to make special buffer tubes specifically for use with the SB15 to make it more 'stable.'
http://www.youtube.com/watch?v=VsP2MKsrZfs

[dangus]

Dumb question from someone who grew up in a blue state:

AR-15 rifles are still legal; why would you mod a pistol into a rifle?

[Joe Brower]

Careful, folks. Remember who you are dealing with.

Don't be surprised if the ATF does a 180 on this decision at any time. Then all these SBRs will be contraband.

[JoeProBono]

[3Fingas]

I was waiting on buying ones of these for my mini draco. I think I will now get one.

[TurboZamboni]

I wonder what ATF will do if they watch me shoot mine from my forehead.

It can be done- upsidedown with an EOTECH.

[kitchen]

What's the reliability with mil spec ammo? Heavy bullets and fast powder would seem to help.