Originally Posted by DazT
I don't think open sights can be considered an "Optical Aid" I think that rule was put in place to stop folk using glasses to reduce blur at close ranges as said above.
opens sights are an aiming aid, and as you have mentioned some rifles have them permanently fixed to the barrel.
However I think if you intend to use both that could be considered an advantage the same as using flip ups on the front of your scope with a hole in it.
Can you even buy mounts that you could see through to be able to use the open sights?
You can buy extra high see through mounts for using open sights with a smallish scope on.
I'm pretty sure the use of more than one sighting system would not be allowed, even if its not explicit in the rules.