“Jingal” was the name the British gave to both Indian and Chinese rampart guns used form the 1700s up until World War II. The guns were originally muzzle loaders, used in fixed defensive emplacements. They had exceptionally long barrels (60″ or more), and were used to fire off rampart walls as a sort of precision artillery. The very long sight radius gave them better practical accuracy than smaller shoulder rifles, and the large calibers used were effective at long range. The massive size of these pieces is hard to describe:
This particular gun is one of the more common types to be found today, a single-shot bolt action in .60 caliber (others were also made in .75 caliber). The gun has a rear sight adjustable for elevation and a dovetail for the missing front sight. The mechanism is a simple interrupted thread at the back of the bolt. The extractor, firing pin, and trigger mechanism are all typical of Mauser type rifles. This rifle most likely dates from the late 1880s or 1890s.
The cartridge is a slightly tapered and slightly bottlenecked black powder design, using an unjacketed lead bullet. Here is an example, with a 7.62x54R and .50 BMG for comparison:
Our friend Bin Shih was kind enough to translate the marking on the receiver, which read “Produced by Tien Jin South Bureau Arsenal in the year of Bing Shen  of Emperor Gung Xu”. The Tien Jin arsenal produced many Jingal rifles, which may be due in part to the presence of Western troops there during the Boxer rebellion.
Chinese Jingal wall gun in .60 caliber (click here to download at high resolution):