I bet if you saw what the scope was doing during recoil we'd all be surprised that it works. I'd imagine it vibrates around pretty good.But it seems to work fine. I don't know about the scope tube question. I've wondered if it wouldn't be a good idea to anchor the end of the rail to the receiver, even with a flexible or compressible spacer that isn't fixed to the receiver. Don't know if it would help or hurt though.