Description: Gun carriage and limber of 10.5cm Prototype is tested by a railway locomotive around a circular track. Gun is then driven across country by a Krupp Kfz 81 6x4 light truck and fired repeatedly at a proving ground. Heavy calibre railway gun visible in the background. Loading procedure. Gun is placed on chassis and moved to a cruciform mounting. Barrel elevated and depressed. Whole gun is rapidly rotated. Shell is loaded and fired and the procedure repeated. Reel Two has coverage of the same trials from a different angle.