In 1958, after several years of development, Roy Weatherby introduced the Mark V bolt action, his first proprietary design developed totally in-house by Weatherby himself and with his head engineer, Fred Jennie. The newly designed rifle had to be built to withstand the higher pressures produced by Weatherby's experimental cartridges, which exceeded . The first Weatherby Mark V actions were manufactured in the U.S. by Pacific Founders, Inc. and the rifles were assembled and finished at the Weatherby facility in South Gate. The demand for the new Mark V rifles quickly exceeded Weatherby's manufacturing capacity, so the company contracted with J. P. Sauer in West Germany to produce the rifles. Manufacturing of the Mark V continued in West Germany until the early 1970s when material and labour costs led Weatherby to shift production to Howa in Japan. Some say the machining and finishing of the Howa manufactured Mark Vs was an improvement over that of the quality of the Sauer made guns. Manufacturing of the Mark V was moved back to the United States in 1995, where the Mark V has been built under contract by both Saco Defense (acquired by General Dynamics in 1998) and Acrometal/ATEK ever since.