The original production rifles by Roy Weatherby were built on commercial Mauser actions manufactured by FN, Brevex (magnum), and Mathieu (left hand). Weatherby would build a custom rifle from a customer's specifications for bespoke rifles, using any action the customer requested - provided the action was strong enough to tolerate the pressures for their desired cartridge. Weatherby manufactured his rifles for many years at his small facility located in South Gate, California, until 1956 when he contracted with Sako to continue building his firearms that were based on the Weatherby-FN Mauser actions. Some custom rifles were still produced in South Gate following this contract.