This looks like a whole lot of fun to shoot. It is based off of the G3 rifle and made select fire and belt fed. It can use an adapter to allow the use of G3 magazines or drums. This one looks to be an H&K 21 chambered in 7.62x51mm. There are other versions in 5.56x45mm and 12.7×99 aka .50bmg. I can’t imagine a .50bmg belt fed H&K 25. That seems monstrous. The rate of fire for .308 is only about 800 rounds/min where the .50bmg is 450 rounds/min.