Hardware Talk: Otis M4 Sight Adjustment Tool

Hardware Talk: Otis M4 Sight Adjustment Tool
The M4SAT nestles down onto the front sight and lets you quickly and accurately rotate it to make adjustments.

The scene was the same in every class. Officers would show up with rifles that were dirty, lacking lube and not zeroed. Not all, but enough of them. Applying oil solved the dry and dirty, but the non-zeroed ones had to be sighted-in.

And that’s when the cursing would begin—cursing at Stoner and the front-sight design, which is so minimalist that it barely exists.

Getting the plunger depressed and then rotating the front sight got to be such a hassle that we dreaded the task. Special tools, a new approach, extra hands­—they were all for naught at times.

Well, Otis has a solution: the M4SAT. The name? M4 Sight Adjustment Tool.

Admittedly odd-looking at first glance, the Otis sight adjustment tool is slick and makes quick work of adjusting the front sight on an AR-15.

This is a special plastic and brass tool that fits onto and over the front sight, depresses the plunger and rotates the sight post, with tactile clicks as it rotates each quarter-turn. The military manuals will tell you that you can use the tip of a cartridge and it can do the job, but that’s often laughable.

So, we end up using small screwdrivers, sections of wire coat hanger or even dental picks, and end up marring the finish or leaving big smears of brass while trying to use a bullet tip.

Well, no more.

Looking underneath the M4SAT, you’ll see a slotted rod made of brass inside the housing, and the housing has a nub at one end.

In use, it’s simple. Just press the tool down with the nub, compressing the front sight plunger. Once it’s fully in place, you can then rotate the cruciform cap to turn the sight. Remember: clockwise raises the point of impact, and counterclockwise lowers it. Once you’ve done the clicks you need, lift and make sure the plunger rests in a notch in the sight.

The front sight on an AR-15 can vary enough from one to the next that the M4SAT won’t work on all of them—but then nothing does.

OK, this is all very clever, but there may be some problems.

One, the cruciform is tactile—yes, but it’s four clicks to a full rotation. Those of you with legacy A1 front sights that are five to a turn will find that the cruciform and the sight don’t always agree. That’s a small problem, and you’ll figure it out.

The second is what’s called “dimensional variance” in tech-speak. No, not the newest Marvel superhero, but that some makers of products aren’t as good about staying within specs as others.

The front sight flange diameter, the size of the notches in the flange and the clearance for the plunger tip, vary enough that in some instances turning the sight is work. I worked my way down the rack and found one rifle (granted, a real crap-tastic Frankengun) that couldn’t fit and turn the sight.

Now, the M4SAT comes in a two-pack, for $18.

Do you need two of these? No, but after your buddy steals one of them (they are that slick), you’ll still have one … and a lesson learned. So, get yours and keep one of them hidden so your “friends” will have to buy their own.

Editor’s Note: This article originally appeared in the June 2024 issue of Gun Digest the Magazine.

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