The 95 mm howitzer M1753, called secret howitzer or Shuvalov's secret howitzer, was an 18th century Russian cannon, a type of muzzle-loading howitzer, devised and introduced into service by artillery commander, General Peter Ivanovich Shuvalov.Shuvalov's gun had an unusual, oval bore, which was designed to facilitate shot dispersal while firing canisters and therefore to increase the killing field.