Doing some research on the Law folder and how it adds 1.3" to the length of pull. It turns out that the ATF has stated that if the LOP on a pistol is over 13.5", you now have created a stock with the intention of shoulder firing. The SBA3 brace and folder combo together put the LOP over 13.5". Evidently this has been known for awhile. Seeing lots of people are filling in the last detent hole on the buffer tube with JB weld and other modifications to prevent the brace from going past the 13.5" measurement.
Read the part here on SB Tactical about the LOP:
https://www.sb-tactical.com/about/compliance-story/
Read the part here on SB Tactical about the LOP:
https://www.sb-tactical.com/about/compliance-story/