Hi All - there has been much speculation about the legalities of pistol-to-rifle conversion units. This troubled me when considering a Mech Tech unit. Upon researching the subject I discovered that a recent BATF ruling lays the subject to rest. Yes - it is perfectly legal to add a 16+" barrel and a shoulder stock to a pistol and then convert back to the original pistol. Mech Tech must have been pestered to death with this question and I see that they have posted detailed info on their forum with all the documentation needed - much of which I discovered elsewhere. It seems that the Mech Tech unit is also legal in CA if it has a 'bullet button' magazine release. Here is their site: MechTech - Home I finally 'bit the bullet' and obtained a CCU from them - shoots great.