Ok, reading this thread was making my head spin so bad i had to create an account to respond to it. First off The ATF does not consider a hand guard a fore grip. infact on an ar platfor firearm its pretty much a requirement. it keeps you from getting burned on a hot barrel, and it protects the gas tube from damage. Yes you can use hold it by the hand guard as well. As far as fore grips on a pistol, vertical grips are not allowed unless you A) pay $200.00 for federal background check and get an NFA stamp for the grip , or B ) pay the $200.00 and register your pistol as an SBR (short barreled rifle) then you can also place a stock on it as well if you wish. You may however use a 45 degree angled fore grip and it is perfectly legal. I also recall someone mentioning not being able to shoulder a pistol. That is false as well. ATF ruled you can shoulder a pistol. They also changed their ruling on shouldering a stabilizing arm brace as well. Since it was determined that a pistol can be shouldered and a pistol with an arm brace is still a pistol, they said "it is ok to "occasionally" shoulder your arm brace if needed to safely or accurately fire your pistol in a specific situation." This of course is a paraphrase ... i don't remember word for word how it was said. The ATF letters i have obtained this info from can easily be found with a quick google search. andif you are looking for a good stabilizing arm brace go with the SB Tactical SBPDW brace. its kind of pricey but its worth it .... it is 3 position adjustable length, makes for excellent shouldering capabilities, and is very short in closed position.
http://blog.roninsgrips.com/atf-letter-stating-magpul-afg-legal-use-ar-pistols/
http://www.thetruthaboutguns.com/2015/01/foghorn/breaking-atf-releases-open-letter-claiming-misusing-pistol-brace-makes-sbr/
