liaison with the armed services l6l 



Frangible Bullet 



Interest in the possibility of using frangible bullets for air gunnery train- 

 ing, so that live targets might be fired upon, was aroused in the spring of 

 1942. After repeated setbacks, which are recounted in Chapter 5 of the 

 history * of Division 2, NDRC, the device was finally perfected. By V-J Day, 

 frangible bullet training was in use in seven gunnery schools in this country 

 and some 11,000 bomber missions had been flown by student gunners in 

 which about thirteen million rounds of frangible bullet ammunition had 

 been fired. The Training Command had directed that all air firing in gun- 

 nery training should be with frangible bullets. 



In the early stages of this project. Ordnance opposition to it, based on its 

 departure from experience in ballistics and on its involving a training situ- 

 ation of potential high hazard, had raised barriers which conventional Army 

 and NDRC liaison procedures seemed ill-equipped to surmount. In the light 

 of subsequent developments, it appears probable that had more effective pro- 

 cedures been available, the frangible bullet for training could have been in 

 use at least a year earlier. 



Hypervelocity Guns and Impro\^d Machine Gun Barrels 



The beginning of work by NDRC on hypervelocity guns was delayed 

 because of the doubts expressed by the Services as to its value. Some objec- 

 tion to NDRC entering at all into this field was expressed by several old- 

 time, influential officers, who felt that this was a subject most likely to be 

 advanced by those of long practical acquaintance with ordnance. The atti- 

 tude was not universal; thus Colonel Glenn F. Jenks, of the Ordnance Tech- 

 nical Staff, prepared a long memorandum on the status of knowledge about 

 gun erosion, which he recognized as a limiting factor to increasing the 

 velocity of guns. He emphasized the desirability of scientific aid, pointing 

 out that no investigation had been made up to that time nor was one in 

 progress which would give an understanding of the mechanism of gun 

 erosion or a practical solution of the problem. 



NDRC's interest in hypervelocity had been heightened by a plea from 

 the British early in the spring of 1941 that this be one of the broad research 

 programs on which American scientists should embark. In particular, the 

 British authorities suggested that research be directed toward an antiair- 

 craft gun that would send a shell to a height of 10,000 feet in three seconds. 

 Considering the drop in velocity with range, this meant a gun with a 

 muzzle velocity of at least 5000 feet per second, whereas the Army's new 

 90-mm antiaircraft gun, then recently adopted, had a muzzle velocity of 

 only 2800 feet per second. 



* In the volume entitled Rockets, Guns and Targets. 



