AR-15 Handguards

[K Frame]

I need to pull the handguard off my AR to reset the gas block.

Are all AR-15 handguard nuts generally the same size?

Or do I need to measure the nut, ring, bolt, whatever it's called and find the corresponding wrench?

[charby]

Which hand guard?

[Boomhauer]

I think the normal plastic ones are. The free float tubes can use a unique one to the manufacturer.

[dogmush]

As Charby implied it kind of depends on the handguard.  *Most* handguards are held to the barrel nut by either screws into the barrel nut, or two screws at the bottom on a pinch type setup. On either of those you just remove the screws and pull the handguard off.

You shouldn't have to remove the barrel nut to reset the gas block.

The mil-spec handguards come off by hand with no tools.

[K Frame]

Which hand guard?

Uh.... the one that guards the hand?

Yeah, I know next to nothing about ARs...

"*Most* handguards are held to the barrel nut by either screws into the barrel nut, or two screws at the bottom on a pinch type setup."

OK, time to take a closer look. I had thought that the upper and lower halves were held in place by a nut.

But, if not, maybe I can take care of this this evening... I need to do a little... preparation... for tomorrow and Wednesday.

[dogmush]

I should edit that to say "*Most* aftermarket freefloat handguards......"

If they are the plastic M16A2 style they are held on my a spring loaded delta ring at the receiver end.  To remove those, field strip, set the upper on a table vertically with the muzzle up and the receiver on the table, pull down (hard) on the steel delta ring that is just above the receiver and pull the handguards away from the receiver one at a time.  They will pivot out on tabs held under the front sight base.


...although if you have that style (upper and lower halves held on by a delta ring) you probably have a taper pinned Front sight base, which begs the question, why would you need to pull the gas block?


I guess we should have started this with "What kind of AR do you own?"

[K Frame]

"I guess we should have started this with "What kind of AR do you own?"

I wish I knew. 

It's a FrankenAR.

The lower I built.

The upper I bought assembled at a gun show from a guy who was selling a variety of cartridge/barrel/handguard variations. I bought an upper that would give me something along the lines of an A2.


Yeah, this is the configuration I have, almost to a T...

So, the ring at the back of the handguard... I pull back on that? (towards the stock end?) It doesn't use a wrench?

https://external-preview.redd.it/EnT7sRnOaEJfQ5olSmRPTJa6ktXO9DBPhziS9WKmtcY.jpg?auto=webp&s=fd657d4c77a74b62b876310203d491700289e7d0

[bedlamite]

Does it look like this? Pull the tapered ring at the base of the barrel back and the handguard comes out in two pieces with no tools

[K Frame]

"you probably have a taper pinned Front sight base, which begs the question, why would you need to pull the gas block?"

A few years ago, after cycling through about 700 rounds, it all of a sudden became unreliable. It would only partially eject the spent case.

I cleaned it, lubed it, ensured the gas tube was clear, everything, and it didn't change the problems I was having.

A couple of people have mentioned that the gas block may not have been tightened down correctly and has slipped.

Is that the problem? No clue. But short of dropping it at a gunsmith to figure out, I figured I'd try making sure that the gas block is in the right place.



"you probably have a taper pinned Front sight base"

I have no clue what that means or how that would be applicable to the issue I'm having. Sorry. 

[charby]

"you probably have a taper pinned Front sight base"

I have no clue what that means or how that would be applicable to the issue I'm having. Sorry. 

Check to see if the gas tube is still pinned in with the roll pin on the gas block/front sight. I had that problem on a build, the pin magically came out and the gas tube was loose, causing ejection issues.

[K Frame]

Is that visible without taking the handguard off?

[dogmush]

"you probably have a taper pinned Front sight base"

I have no clue what that means or how that would be applicable to the issue I'm having. Sorry. 

On an A2 style upper, the front sight and gas block are one piece in that classic "A-Frame" M16 front sight.  That part is called a "Front Sight Base".  Sometimes abbreviated on Forums as FSB.  Normally, that style of FSB is the one that goes with the plastic handguards that have an upper and lower half.  If that style of FSB is installed correctly, it is held in place by two taper pins that are driven through the FSB into groves that were drilled into the barrel on initial install.  You can see those pins on bedlamite's pic if you squint.  They are directly above the bayonet lug and on the on the piece under the barrel directly forward of the handguards.  These FSB's don't often get loose, and aren't really easily fixable if they do.

If you don't have an integrated front sight, you are more likely to have a gas block that is held on by set screws or a clamp set up.  Those or more "fixable" but are less likely to have the two piece handguards.  Although there are some models out there with Milspec style guards and gas blocks, so it really depends.

[dogmush]

Is that visible without taking the handguard off?

Is the gas block under the handguard?

[dogmush]

Gas tube roll pin goes there:

It's very small.

[bedlamite]

https://www.youtube.com/watch?v=vhqkowLkUow

[K Frame]

Hum.... OK, so I've got to go home and see what I have on this upper...

If it is the front sight unit, and the roll pin is still there...

Then what?

[charby]

Hum.... OK, so I've got to go home and see what I have on this upper...

If it is the front sight unit, and the roll pin is still there...

Then what?

Remove the hand guard and make sure the gas tube is still secure.

[bedlamite]

Hum.... OK, so I've got to go home and see what I have on this upper...

If it is the front sight unit, and the roll pin is still there...

Then what?

Go home, take a pic, post it, then tell us what your end goal is.

[K Frame]

"then tell us what your end goal is."

Well...

Step 1... Fix AR.

Step 3.... PROFIT!

The goal is to get it back to being as reliable as it was for the first 700 or so rounds when it bobbled maybe twice, instead of just about every shot.

Otherwise it's a pretty long, and not particularly attractive, paperweight.

[bedlamite]

If it's a pinned gas block, removing it won't help unless you change to a clamp on style gas block.

There's more to it, Is the gas key loose or plugged? Do the gas rings hold the weight of the bolt?

https://www.youtube.com/watch?v=I_9913p57Us

[Perd Hapley]

So there are people out there with 2-piece, drop-in handguards, and they've never taken them off? That would not have occurred to me. We did that every time we cleaned them.

[K Frame]

"Is the gas key loose or plugged?"

Good question. I didn't know that gas actually entered that part. Another thing I'll check when I get home this evening.


"Do the gas rings hold the weight of the bolt?"

Up until about 15 seconds ago I didn't even know that the AR had gas rings...

But, in the limited reading I've done on what they do, I wouldn't expect them to cause a day/night problem. I'd expect it to grow over time.... wouldn't it?

[bedlamite]

"Is the gas key loose or plugged?"

Good question. I didn't know that gas actually entered that part. Another thing I'll check when I get home this evening.


"Do the gas rings hold the weight of the bolt?"

Up until about 15 seconds ago I didn't even know that the AR had gas rings...

But, in the limited reading I've done on what they do, I wouldn't expect them to cause a day/night problem. I'd expect it to grow over time.... wouldn't it?

Contrary to popular belief, the AR is not true DI, it's actually a piston driven gun, it's just that the piston is the bolt inside the BCG.

[K Frame]

So there are people out there with 2-piece, drop-in handguards, and they've never taken them off? That would not have occurred to me. We did that every time we cleaned them.

I never served in the military, and have never had that much interest in the AR platform. I started a desultory build on one about 15-20 years ago because prices were way down and Mtnbkr got me vaguely interested.

Glad that I did, but still not a lot of interest in the platform.

[Perd Hapley]

I never served in the military, and have never had that much interest in the AR platform. I started a desultory build on one about 15-20 years ago because prices were way down and Mtnbkr got me vaguely interested.

Glad that I did, but still not a lot of interest in the platform.

I never had that much interest, until I decided to build one. That can be pretty cool.

If you aren't rolling around in the dirt with the gun, you're probably fine leaving the handguards on. That stupid delta ring is a pain to deal with.