The folding butt and the foregrip are spring loaded to dampen the heavy recoil from shoulder launching a grenade. The optic is set up for grenades and not ammo. They come with ten round mags for the grenade blanks.

As far as I know this is the only kit built semi. From what I was told, there were six dealer samples brought into the USA, two were cut into kits and this one built into a working semi. So there is one other kit out there and four other examples. Not sure, but I think the fulls went to .gov as samples/examples for the military or BAFTE/FBI... Anyway, I've never seen another one...