AR-15 gas port alignment

DutchV · Jul 25, 2021

A different approach to gas port alignment. The pin gage is .101", the same size as the gas port. My Teslong boresope didn't give a clear view so I drilled an access hole. MicroMOA (now defunct) used to do this on their adjustable gas blocks. I'll install a set screw later for support.

engineerbrian · Jul 25, 2021

I have the Teslong bore scope too and yeah, this is the one thing it doesnt do well. Check out Chads youtube channel, he has a work around for this issue.

DutchV · Jul 25, 2021

engineerbrian said:
I have the Teslong bore scope too and yeah, this is the one thing it doesnt do well. Check out Chads youtube channel, he has a work around for this issue.

That does look like a good solution. Of course, I saw the video about a half hour after I finished the job.

alucard0822 · Jul 26, 2021

Set screw blocks are easy, get a dimple jig, you will always have a dimple centered exactly opposite of the gas port, and line up with the set screw away from the muzzle. Can always use "the spaghetti trick". Put a peice of thin spaghetti in the gas port bottomed on the far side bore and snap ot off. Put the gas block in place, more it in position upside down, the spaghetti will fall into the gas path in the block, move.it around and center it. When all is well, snap it through the bore with a cleaning rod, let the peices fall out.

SkiPatrolDude · Jul 26, 2021

Is this really necessary?

Dimple jig?

Frankly I’d rather eyeball it than do it that way.

DutchV · Jul 26, 2021

alucard0822 said:
Set screw blocks are easy, get a dimple jig, you will always have a dimple centered exactly opposite of the gas port, and line up with the set screw away from the muzzle. Can always use "the spaghetti trick". Put a peice of thin spaghetti in the gas port bottomed on the far side bore and snap ot off. Put the gas block in place, more it in position upside down, the spaghetti will fall into the gas path in the block, move.it around and center it. When all is well, snap it through the bore with a cleaning rod, let the peices fall out.

Couldn't find any pasta large enough for a .101" gas port.

And I don't have a dimple jig for a .875" gas block journal.

atblis · Jul 26, 2021

Consider doing the same thing you did and have always wondered why it isn’t that way

Did you adjust your Teslong camera by moving the mirror? Illuminating through the gas block also helps. With a couple tweaks the Teslong camera works great for this.

Rockzilla · Jul 26, 2021

alucard0822 said:
Set screw blocks are easy, get a dimple jig, you will always have a dimple centered exactly opposite of the gas port, and line up with the set screw away from the muzzle. Can always use "the spaghetti trick". Put a peice of thin spaghetti in the gas port bottomed on the far side bore and snap ot off. Put the gas block in place, more it in position upside down, the spaghetti will fall into the gas path in the block, move.it around and center it. When all is well, snap it through the bore with a cleaning rod, let the peices fall out.

and it works.... how many have little pieces left in the box, I know
some just dump the box in the pot.

-Rock

csxt602 · Jul 26, 2021

atblis said:
Illuminating through the gas block also helps. With a couple tweaks the Teslong camera works great for this.

I did this a few weeks ago to check the gas port/block alignment on my son's AR, and it worked like a charm. That's the one issue that Chad from SOTAR mentioned with the Teslong scopes, the fact that they didn't illuminate into the gas port to check the block alignment.

atblis · Jul 26, 2021

It definitely works better, but I've been able to get it done pretty easily with the built in lights. The trick is to screw the mirror down closer to in effect move the focus further away from the camera.

mvee · Jul 26, 2021

I’ve found a pretty good way to align the gas ports in the barrel and gas block. It’s easier to look at the pictures than to describe what’s happening. The pictures are out of order too.

I get a piece of rod that is the diameter of the hole they drilled for the gas port in the gas block. Sometimes it’s the size of the tap drill for the 10-32 screw. I stick this in the gas block and scribe how much of the can fit on the blind size of the gas block. Usually it’s like 1/4 to 3/8 of an inch or so.
I cut it off and give it a cone on one side. A lathe is nice but a drill press and file will also work.

I put the little plug in the far side of the gas block. I then install the block on the barrel. I get it approximately aligned and then push the end of the plug that I can see through the gas tube home into the barrel gas port. It will self align. I then can tighten the set screws.

AR-15 gas port alignment

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