Re: RIS mounted fixed front sight.
I had this setup for years on my go-to rifle. It is suboptimal in theory, because of the possibility of the rail rotating slightly or flexing under load. However, It worked well for me out to 300m. I used it without any optics, irons only, until about 2 years ago, when I mounted a 2-7x and offsets irons. Within the ranges that iron sights don't suck, a good rail with a front sight on it isn't a problem in my experience. Has to be a really solid one, though. Same gun has offset irons on it today that have been holding zero, also.