Weapons Captured from the United Kingdom and the United States
The German army was exceedingly frugal when it came to equipping troops with firearms and other equipment. Huge stores of foreign war material were captured as countries were annexed, conquered, or as enemy troops were defeated. Some of these weapons were reissued to German soldiers as substitute standards. British and American weapons were among the least employed by the German army. While large amounts of British weaponry was captured during the conquest of France, culminating in the evacuation at Dunkirk. There was simply not a steady enough supply of captured material to make it the most useful and suited to reissue to German troops. One exception would be the Sten submachine gun. Chambered in 9mm it was easily supplied by the German army who employed this caliber themselves. the Headquarters section of the 353rd Infanterie Division was outfitted with a number of captured British Stens. Other weapons were used situationally and only issued to the most reserve of reserve troops.
In the case of these photos, it is impossible to tell without more context if the soldiers were issued these guns, using them without orders, posing with them as curiosities, collecting them for disposal, or anything else. We cannot merely assume that the fact that we see a soldier holding a foreign gun the German soldier pictures was actually issued it or even using it for any prolonged period of time.