The Florida Attorney General, Ashley Moody, has issued an opinion clarifying that the Florida legal definition of a "short-barreled rifle" does not include a pistol to which a stablizing brace has been attached, even if the stabilizing brace is used as a stock. From myfloridalegal.com:
Unless and until judicially or legislatively clarified, I conclude that the definition of "short-barreled rifle," which the Legislature enacted in 1969, does not include a handgun, such as a pistol, to which a person attaches a stabilizing brace, because the use of a such an optional accessory does not change the fundamental characteristics of the handgun.
The Florida statute banning the possession of short-barreled rifles was passed in 1969, shortly after the Gun Control Act of 1968 was passed by Congress at the urging of President Lyndon Johnson. From Florida Statutes 790.001(16)
(16) "Short-barreled rifle" means a rifle having one or more barrels less than 16 inches in length and any weapon made from a rifle (whether by alteration, modification, or otherwise) if such weapon as modified has an overall length of less than 26 inches.
The short-barreled rifles were added to the federal National Firearms Act in 1934 as an afterthought by the actions of an addled, drunk, or Machiavellian Minnesota Congressman, Harold Knutson. .....