This post is a placeholder for generational changes that the Umarex Notos has and will go through.
Gen l has two threaded holes on the receiver top
Gen ll only has 1 grub screw on the receiver top
Gen lll has 1 grub on the receiver and adds a degass grub on part 42
Gen lV has 1 grub on the receiver and adds a degass grub on part 42 & splined pins have been replaced by threaded grub holes retaining straight pins
Gen l has two threaded holes on the receiver top
Gen ll only has 1 grub screw on the receiver top
Gen lll has 1 grub on the receiver and adds a degass grub on part 42
Gen lV has 1 grub on the receiver and adds a degass grub on part 42 & splined pins have been replaced by threaded grub holes retaining straight pins