A company recently got into hot water for having a folding BRACE on an AR PISTOL, with a forward grip attached. The forward grip, if the weapon is not 26" or longer, makes the weapon an "AOW" and is therefore no longer a pistol, and requires a tax stamp, according to the ATF AT THAT SPECIFIC instance. The ATF actually tracked down owners of the AR Pistol and confiscated their weapons. The reason is because though the weapons with brace unfolded were 26", as rifles length is measured, they decided to measure with the brace "folded" on the pistols in this case. THUS, i'd be careful with a stock that collapses like that and measure it at the shortest possible configuration (remember muzzle device as well) and remove a front grip if it does not measure 26" at that point.
