Good luck with it...
Ive owned several AR7 variants over the yrs from original Armalites thru Charter Arms, a late model Henry...and a very mysterious no name version ( this rifle had zero markings on it for manufacturer/model/serial number etc....had a rough texture exterior on the receiver....it wa suggested to me that it was a run produced for the USAF ??)
NONE of them ran reliably..some were totally non functional....one of the Charter arms versions ran reasonably with specific ammo only.
They were a great idea very poorly executed and even further poorly manufactured/constructed with materials and parts quality substandard even in disposable household products league.
Unless you have a soft spot for the look or history of these lil buggers....pass and and buy a Marlin Papoose or Ruger takedown.
Neither of these will float...but they will actually work, have no inherent flaws, are accurate and parts can be sourced easily.
Similar idea executed properly...aside from the floating part...
You've been warned.....