Ar Gas Block Replacement

[Brundoggie]

I tried to search but didn't find anything (maybe I wasn't holding my mouth right) so I'll go ahead and ask.

I want to replace the front sight/gas block on my flat top upper with a low profile gas block. Is this a job for amateurs (AKA - ME!) or should I reconsider.

Any opinions would be appreciated. Any detailed instructions and cautions would be be appreciated even more.

[uscbigdawg]

1 - Remove flash hider/muzzle brake (if applicable)

2 - Tap out the taper pins on the front sight base

3 - Remove front sight

4 - Measure the diameter of the barrel at the sight

5 - Put on corresponding gas block (JP RULES!!!)

6 - Test fit before tightening down allen head screws

7 - If everything's happy, apply some Loc-Tite and thread/tighten scews

8 - Replace flash hider/muzzle brake

Done.

I don't think I missed anything, but part of me believes I did. I know that I didn't mention to make sure the gun was unloaded, and that it's mounted in a firm vice with a block, but figured you might know all that.

After that, go to the range and tune 'til the rifle is rockin'!!!

SPC Richard A. White, Senior Medic

249th MP Detachment (EACF)

Camp Humphreys, ROK

[ryan45kim]

If you don't need a rail on you're gas block then just cut off the front sight with a dremal tool.

If you look at bushmasters rifles that is what they are doing.

I've done two Ars this way and they work great, plus I can take off my freefloat tubes they will go over the cut down front sight.

[AK74]

First you will need to remove the gas tube.

There is a small roll pin that must be driven out on the gas block.

The gas tube can now be pushed back in to the upper, next rotate it to clear the gas block then remove it from the rifle.

If you can't pull the tube out buy hand, lightly clamp the tube with some small vice grips, and then tap on the vice grips lightly with a hammer to free it from the gas block.

I would also buy a new gas tube roll pin, they are cheap and often damaged during removal.

Edited December 4, 2005 by AK74

[ryan45kim]

Also if you are taking off the front sight / gas block the retaining pins (the two bigger pins on the bottom) are tapered so you can only drive them out in one direction.

Use a big hammer (I use a 5lb dead blow) to start the pins they are very tight and if you tap on them with a light hammer you will pean them over.

[PacMan]

First you will need to remove the gas tube.

There is a small roll pin that must be driven out on the gas block.

The gas tube can now be pushed back in to the upper, next rotate it to clear the gas block then remove it from the rifle.

I would advice against that. Much easier to remove the front sight tower/gas block and gas tube as a unit, then if you want to reuse the gas tube, remove it after the unit is off the upper.

[AK74]

I would advice against that. Much easier to remove the front sight tower/gas block and gas tube as a unit, then if you want to reuse the gas tube, remove it after the unit is off the upper.

Interesting, I never even considered removing the gas tube / gas block as a unit.

To be honest I have only swapped out a few gas blocks, but I have installed more then a few barrels into upper receivers, the first thing I do after removing the hand guards is to remove the gas tube when removing a barrel and it’s the last thing I do when installing a barrel. The tube is easily bent so I like having it out of the way first thing

I least for me the easiest step in removing a pined on gas block is removing the gas tube.

Don’t see how it could be any easer your way, but I will admit there’s more then one way to skin a cat.

[Chuck Merriam]

Don't cut down your front sight gas block! If you have a fixed sight gas block that came on the gun, it was fitted at the factory with the roll pins. If you ever want to sell the gun or it's intended use changes you can put it right back on and it will be set for windage (for the most part). Find a gas block at a show to cut down, or order a low profile. I think you will be happy you did later. JP gas blocks are great, and you may want to consider a Yankee Hill Machine flip up front to have the look and the function.

[ryan45kim]

I’ll give you the resale value for cutting down the front sight but not windage.

If you’re barrel was setup properly at the factory and you are using a factory replacement sight you should have no problem with windage, I never did (if you get some cheap knock off part that’s a different matter).

I’m not a fan of flip up sights for competition, if you loose you’re main sighting system you’re dead already now if I was in a real world situation that $100 plus flip up front sight would be worth it.

I’m not trying to start a fight but front sights are cheap, and I feel much safer with roll pins holding it on (those set screws always worried me there is a reason they cover those gas blocks in lock tight when they install them).

Also I can take my free float tube off (it slips right over the cut down front sight).

Just trying to help save some money that you can use for ammo, just my two cents.

[tewlman]

I have a MSTN gas block and it is the slimest low profile block I have ever seen. I would suggest you check it out before you cut your factory block or buy another. If you use optics it isthe way to go. On my competition rifle I have no need for backup sights, like ryan45kim said, if you have to switch to backup sights on a stage you might as well forget it.

[IPSCDRL]

This explains it and has pretty good pictures as well.

http://www.varminthunters.com/ar15tech/fre...5freefloat.html