In 1949, Israel was still fighting its was of independence, and purchasing arms internationally was difficult to do. The recently-formalized IDF wanted sniper rifles, and looked to Hammerli in Switzerland for a variant of the K-31 straight-pull bolt action action. Two different models were purchased; 100 of the ZK-31 with 4x Kahles scopes, and 100 of the FK-31 with target diopter sights. The Swiss could not legally ship them directly to Israel, and so the order was placed for Nicaragua instead. Mysteriously, the freighter carrying the rifles somehow sank off the coast of Egypt, and the guns ended up in Israeli hands. They were taken into IDF service, and saw use in the early days of Israeli independence.

The style of optics mount on these rifles is also pretty interesting aside from the history of the guns...