I have read about the Indian rebellion of 1857, and have learned that the specific reason that triggered the rebellion was the assumption that cow or pig grease was used to lubricate the cartridges for the Enfield rifles introduced in the British Army in India in 1857. Since to be used the cartridges needed a membrane to be broken with the teeth, the Indian soldiers considered that the use of the animal fat was offensive to their religious beliefs. Although the British denied that the grease was of animal origin and even tried to replace the cartridges with others whose grease would be made by the cipayos themselves, the rumor did not vanish.
This reminds me of a story I heard many years ago. A commission from some arabic country was interested in purchasing some surplus 7,92 mm ammo from a Spanish arsenal. But they rejected the deal in horror after being shown some cartridges and finding that the primer seals were green in colour. Now this is peculiar because the green color is a sacred one in Islam, as it expects paradise to be full of lush greenery.
Maybe what they didn’t like was the sacred colour to be associated with war material. Who knows.