If you like forward-mounted optics, there is another option that will still allow you to use your irons -- the Ranch Products Scout Mount. It's been around forever, and is half the price of the handguard-replacement rails.

I'm using a handgun scope, as the Ranch Products mount requires a long (longer than your typical "Scout" scope) eye relief.
Although, if you need to remove your handguard for cleaning (as I typically do...), you will have to modify it a bit...
