ar-556 gas block

[cleardatum]

it became apparent at the range last weekend that the gas block/front sight on my ar is interfering with my scope image. rather than hack the sight off, i'd much rather change the gas block. is this difficult? i am mechanically gifted, and have most of the typical ar tools, i've just haven't tackled this gas block job yet...

 

[Chuck 100 yd]

There are several youtube videos covering just that. It's not very dificult at all but you have to be sure the parts are compatable as there are many different configurations of the AR. A call to the guns maker may answer many questions.

Rereading your post, I assume your gun is a Ruger AR-556. Ruger wont be any help about you wanting to modify the gun. I have a Leupold VX1 2-7 on mine and the front sight is not visible in the field of view. What scope did you mount? And is it mounted high enough?

 

[cleardatum]

it is a ruger. the scope is a leupold ar 1.5-4 fire dot, mounted on a burris p.e.p.r., so it's not that low. the problem is the front sight is tall, and that scope has a depth of field that is nothing short of amazing (you can point it at the ground, and the image is clear). unfortunately, that contributes to the problem with the front sight. at 1.5 magnification, the front sight is clearly visible, and at higher magnification, i see a diffraction pattern.

 

[Chuck 100 yd]

That would be distracting. A few calls to suppliers of gas blocks without the sight should locate what you need. It would be helpfull to know the diameter of the barrel at the location of the gas block though. Good luck !

 

[RoninPA]

The front sight base/gas block is pinned in with taper pins. You can drive them out to remove the FS/GB, make sure you check and drive them out from the pins small side to the pins larger side (small side should be on the left side of the rifle). If you have access to an AR FS bench block it makes things a whole lot easier. Be aware, you might have to smack the pins pretty hard to get them started.

You will have to remove the flash hider to get the FS off the barrel and to get the new GB on. The flash hider should take a 3/4" wrench. When you replace the flash hider you may also want to replace the crush washer with a new one (but the old one may be ok to use again, your option, myself I like to put a new one on).

The barrel of the Ruger AR556 at that point is 0.70" diameter so that is what you will look for in a new GB. You can get GBs that are pinned on but I would get one that has the two set screws on the bottom, it's just a lot easier to work with.

 

[Chuck 100 yd]

There ya go. Great to have a man who knows these things for sure. I agree on the gas block that is held by set screws. You will need to take some carefull measurments to make sure the gas ports align and that your gas tube is properly seated and pinned in place.

 

[cleardatum]

thanks for the advice and tips, everyone. i got the appropriate tools, and, start to finish, it took about 90 seconds (maybe a little longer). the sight picture is now... AMAZING.

 

[Triggernosis]

On my competition Service Rifle I sawed mine off with a hacksaw and touched up the bare steel with some flat black spray paint. Less trouble than anything else.

 

[Galaxiedan]

I have the same issue, where do you find a .700 gas block? I keep finding .750 as the closest

 

[cleardatum]

I have the same issue, where do you find a .700 gas block? I keep finding .750 as the closest

i find three sizes only- .625, .75, and .936. how are you measuring?

 

[Galaxiedan]

I have the same issue, where do you find a .700 gas block? I keep finding .750 as the closest

i find three sizes only- .625, .75, and .936. how are you measuring?

quoted from above

"The barrel of the Ruger AR556 at that point is 0.70" diameter so that is what you will look for in a new GB. You can get GBs that are pinned on but I would get one that has the two set screws on the bottom, it's just a lot easier to work with."

I didn't actually measure, just going off the previous post that stated the barrel was .700, after further research it appears it is .750

 

[RoninPA]

That was my mistake in my post, I had measured the barrel just ahead of the GB and should have said that since the barrel at that point was 0.70", it then steps up where the FSB/GB mounts to 0.750. Sorry for the confusion I might have caused, I work on a fair amount of AR's so I know that if the barrel in front of the FSB/GB is a certain measurement then I know what size a replacement GB typically needs to be installed, I just forgot to say that.