Zak, I have a vz 58 with the pinned on barrel extension. I would like to send the rifle off and have a muzzle break put on and permanently attached. The issue I'm running into is when the barrel extension is removed the barrel length is under the legal limit. If the barrel extension is going to be removed and immediately replaced with a permanently attached muzzle break (over the legal 16 inches) is SBR paperwork required? All work would be done by a licensed FFL SOT dealer. I'm being told I need to get SBR paperwork even though the barrel will be over 16 inches when the job is finished. I'm told the barrel itself cannot be removed from the receiver to circumvent this issue due to the way it is attached. If that is the case then I will just have my FFL chop the barrel too. Do I need SBR paperwork? Thanks.