Thats easy, they are Swiss.
Its a Swiss STG57(510), the rifle on the right with the green forend is probably a 540, could be a 550 though hard to tell. The 57 replaced the awsome K31, which was than later replaced by the modern and even more awsome 5XX series.
The Swiss only recently adopted NATO rounds, the 57 was chambered in 7.5 Swiss, except for the ones exported.
The 57 is out dated, essentialy cheap surplus. If I remember correctly they are licensed by Sig to make the 540. But they are both some of the best rifles you can get.