Greetings gang, as we all know, the ATF's new rule concerning pistol stabilizing braces is in effect and we have a 120 day amnesty period to file a Form 1 for an SBR registration sans $200 permission slip fee. Here are a few things to keep in mind if you're planning on SBR-ing a brace equipped pistol:
1 - Once approved, there are additional potential pitfalls; you can't go across state lines without first obtaining clearance from the ATF; if you are moving to a new residence, you again have to notify the ATF.
2 - THE BIGGER ONE - if the pistol that you will be converting to an SBR is imported (ex. HK SP5; Century AP5; Zenith imported Z5; many AK variants), you should probably also brush up on what you need to do to be compliant with 18 U.S.C. 922(r) with respect to the number of parts that are imported vs. American.
3 - If you elect to SBR and remove the brace and replace it with a stock, it has to have the same rear surface area as your brace.
Just a couple pointers to keep you out of Club Fed. There are certainly other potential pitfalls, but due to work commitments and having just had surgery, I haven't had an opportunity to really fine toothed comb read the entirety of the rule as published to the CFR.