Fixed barrel mounted front sight for an M&P15-22

[brothermatthew]

I bought a 15-22 last year because I wanted something that I could use for training, so working bolt release, drop free magazines, etc and that was utterly reliable. The 22 conversion kit I had just wasn't cutting it. I have been thrilled with my 15-22 which has been amazingly reliable and accurate enough I was able to get my Rifleman at an Appleseed shoot. That said all my issue rifles are M16 or M4s and thus have fixed front sights, which has a distinct sight picture. So I was never quite happy with the flip up or rail mounted front sights on the 15-22. And I learned at my Appleseed shoot that a tight sling flexes the forearm enough to move the point of impact since it moved the rail mounted front sight. So I decided I'd do something about that.

The problem though was that a standard A2 front sight is made for .750 bases. I didn't want to try to make shims to fit the .660 22 barrel. Then I ran across the Doublestar A1 front sight towers in the new Brownells catalog. The A1 barrel being .625 I figured I could remove enough metal to fit it on the 15-22.

It was fairly straight forward and the work was almost all done with a vise, gauge and a dremel tool using slightly worn sanding wheels. The worn wheels meant that I wasn't going to get too focused on the flying sparks and cut too much. It took maybe 45 minutes of work, including gauging regularly until I was able to fit the block to the barrel.

To affix the gas block to the barrel I wanted to try something fairly simple so that I didn't have to pin the already small diameter barrel. So I used the whole under the sling mount on the sight to mark the barrel then drilled a dimple into the barrel. I used the rail mounted front sight I had to make sure the alignment of the A2 base with perfect. I used that again when it came time to mount and tighten the set screw for the sight to prevent any cant.

Next I used an 8-32 tap on the hole, sanded the rough spot on the inside of the gas block left by the die and was good to go. I fit the sight back onto the barrel and used some loctite on both the barrel around the gas block and on the 8-32 set screw. And now I have a fixed sight on my 15-22 and it works very well. I though not being an F marked front sight base might cause issues and require a taller front sight post but wasn't an issue.

I have been thrilled with the results. The rifle now better recreates the set ups on my work, and my private training rifles. Accurate when using a sling since a flex in the forearm now longer has any impact on the front sight. Since folding and rail mounted front sights are so common now I don't expect this to be a popular mod but I did want to share. Any questions or comments are more than welcome.




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