The Sauer 303 is a semi-automatic rifle line available in calibers from 7x64mm to 9.3x62mm.
[1] The J. P. Sauer & Sohn company is a manufacturer of very high quality firearms and partnered with SIG (now Swiss Arms) in 1975 to create the Swiss/German based SIG Sauer company which is parent of the US based SIG Sauer.
Like Swiss Arms, and SIG Sauer, J.P. Sauer & Sohn is also owned by de:L&O Holding