I tried a few different optics and mounts on mine since doing the mod.
With just the stock AR buttstock the iron sights line up well but I wanted to mount a red dot.
The ARMS 18 mount positions the optic a little higher than the Ultimak M8 .
The Eotechs mount a little higher than the TRS and spacer combination I used .
I first tried an Arms 18 mount with Eotech , then an Arms 18 with a Bushnell TRS-25 and and finally the Ultimak M8 front rail with an Eotech and then the TRS -25
Using a stock AR buttstock with no cheek riser and the Ultimak M8 with no spacer on the TRS-25 I can cowitness with the iron sights .
When looking through the peep sights and the TRS at the same time it has a small field of vision but I have shot it out to 600 yards like that .
Using a small spacer on the TRS mounts it above the iron sights so the field of vision is a lot better and the 3/4 in cheek riser on the Magpul buttstock I mounted gives it a good cheekweld .
If I was using the Eotech on the Ultimak or ARMS 18 a higher cheek riser on the butt stock would be required than the 3/4 inch one on it now .
This is my favorite setup for this rifle now.
