My only complaint about the Magpul MBUS sights has always been the front sight post. On my .308 I swapped out for a Trijicon tritium post (See that thread HERE ). I realized quickly that was a waste as I don't shoot at night, and tritium doesn't do much for me during the day. Based on online reviews, I tempted fate, and purchased a Mounting Solutions Plus "Sightlink" fiber optic front sight post. I guess I was lucky with the Trijicon post as that was a simple drop in part... Not so with the Sightlink! While it is threaded the same, that is where similarities end. 1. Sightlink requires it's own front sight detent. 2. Above said detent does not fit in a Magpul MBUS, which uses a special polymer detent. 3. God's greatest gift, after fire, was the dremmel! I will not be deterred! Sorry I didn't take pictures as I worked. First I had to create a detent hole. I dropped in the rotary tool and made a perfect fit. Next, I fount the detent was too long for the hole and I couldn't adjust the sight post down far enough. Again I went to the rotary and I cut about 25% off the bottom of the detent. I cleaned up the edges and it fit perfectly. Last was the grueling labor part. The nipple on the detent was out of alignment due to space confinement on the sight. I couldn't move the detent any further without risking the integrity of the sidewall. Using a small file, I carefully took off about 1/3 of the detent nipple, creating an offset nipple. This was painstaking work as I filed, check for fit, filed, check for fit, filed..... Eventually I was able to make a perfect fit and I am ecstatic about the results! A little more about this sight post. This is the "Match Grade" sight. It is considerably thinner than the mil post. It also has 8 adjustment points instead of 4. The top and bottom of the post spin freely from each other so that the fiber optic can be aligned with your line of sight. This sight also comes with replacement fiber. I have two 4" strands of fiber (one in red and one in green) that I can use to replace. Simply push it out with a pin, slide in a new one, then hit one end with a lighter to secure it in place. So far it looks really good, and is a hell of a lot brighter during the day!