Do the sights work with the scope removed? they look lower than the cantilever mount.
Is the barrel non removeable since it was pinned?
Yes the sights work with the optics removed. It's actually a pretty cool set up. With the rear sight flipped up you get a pretty fine sight picture. You can also flip the rear sight down and use the channel in the cantilever for close and fast.
So you are correct. The sights are below the cantilever. But were designed to work that way.
