John Browning Patent 577281
Again like the two previous John Browning Patents, this one involved a pump action 12 gauge shotgun design. Winchester owned the rights to this design, but never manufactured it. John Moses Browning was granted US Patent 577281 for this design on February 16th, 1897. It had been applied for on March 16th, 1896.
Even though there is not a lot of information available on this patent, it appears from reading the patent description that it provided a safety design preventing the premature opening of the bolt between the time the trigger is engaged and the time the round is expelled.