Hello, im interested in purchasing a 14.5 inch barrel and pin the flashider to comply with NFA. Is it legal for me to buy the barrel online and have a flashhider pinned at a local dealer when the barrel arrives in the mail. Looking at these websites that sell NFA barrels, they say "all NFA rules apply" with SB's, but i would assume the majority of these online retail stores will not pin a flashider before shipping due to them just being distributors and not manufacturing facilities. Help?