As noted in my previous post, I am new to the AR15. My new gun has a top rail and fixed front site. I immediately added a flip up rear site. With this addition everything lined up perfectly, right out of the box. I already own a Sig STS 080 Red Dot. Will this mount directly on the rail, or does it need a filler to raise above the front site? I assume some adjustment will be required to zero the red dot... On most guns I see the flip up rear site in addition to a range of optics. How do I use the iron sites, after the red dot is mounted? I am also considering a magnifier. So the rail will hold, flip up iron site, magnifier, red dot. Is this normal? It seems to be the trend on the guns I have seen.