 These tests demonstrated several problems, including poor shot-to-shot performance of the decades-old gunpowder, and the fact that the projectile left the barrel so quickly that the powder did not have time to burn completely.New charges using modern powder were soon supplied, and by November 1962 the 150-kilogram Martlets were being fired at over and reaching altitudes of .The Martlets evolved through this period, growing in size and sophistication.