AR Gas Block and handguard questions

[bgrav321]

I have a M&P 15 Sport. I have changed out a few things that helped like a handguard and pistol grip for my big hands, but I'm wanting a longer handguard for a few reasons.

1. I'm 6' 6'' and my arms are long. I need my left hand further out on the barrel to shoot comfortably and faster with greater accuracy.
2. I change out between optics and irons depending on what kind of shooting I'm going to do that day. I would like a longer sight radius for irons, and I want to change out the stock front sight with a flip up both for use with the optics and because the front sight post that came with the rifle is too thick. I need something with more precision.
3. I may end up sticking a bipod on there one of these days. With my current setup if I mounted a bipod on the handguard I would have no place for my left hand when shooting offhand.

I know that some people say just saw off the existing front sight. I really don't want to do that. I have also read that there is a low profile setup you can get to replace the existing gas block that will fit under the rifle length handguard (??). Call me crazy, but I actually want a rifle length, not a mid length handguard, and would like to stay with Magpul because I like the MOE handguard I have on it currently. I am open to suggestions on this front, but am really not a quad rail fan.

So. How would I go about installing such a thing, and what would be the parts list to make it happen? Just for clarification, my rifle has a fixed front sight gas block and a carbine length gas system.

Thanks in advance,

bgrav

 

[fatcat4620]

The only way to keep the magpul would be to go to a dissipator set up. A new upper would be the easiest way to go.

 

[velocette]

bg;
Get yourself a rifle length handguard that suits your fancy, buy a low profile gas block & a clamp on front sight.
Measure the diameter of your barrel in front of the gas block & buy the clamp on front sight for that diameter. Mount the front sight as far out on the barrel as you can.
What you'll end up with is a rifle set up with a longer sight radius which will make it easier to shoot accurately with. I think that you will be better off finding a free float handguard, such as the Model 1 or Magpul also makes them.

Roger

 

[bgrav321]

Velocette,

So you're saying to remove my existing front sight and replace it with a low profile gas block. But for the clamp on front sight, is there another thing I can clamp on the front besides a fixed front sight? I would like to have a flip up front sight if possible.

 

[rcmodel]

I'd go with the long handguard.
Low-Profile gas block under it.
And a rail height clamp-on BUS front sight on the handguard rail.



rc

 

[bgrav321]

So what then does the handguard fit into on the muzzle end of the forend?

 

[rcmodel]

It doesn't.

It is a free-float handguard attached only to the upper receiver.

rc

 

[NeuseRvrRat]

the configuration you're talking about is referred to as a "mock dissipator". google "MOE mock dissipator" and you'll see what you're looking for. it'll be similar to this:

rc, he said he wants to use his MOE handguard, which means he will need a gas block with a handguard retaining cap.

 

[bgrav321]

Really appreciate the answers so far thanks guys.

@NeuseRvrRat and rcmodel, So is there a low profile gasblock with a handguard retaining cap and no front sight attached?

 

[rcmodel]

Not that I'm aware of.

And it wouldn't work with what you are trying to do anyway.

In order to get a longer handguard like you want, it has to go out past where your present one ends. And the low profile gas block has to go inside it because that's where your gas port in the barrel is located.

The only way around that is to buy a new dissipater barrel with the gas port drilled further foreword at 20" rifle length then your 16" carbine barrel.

Then you could use a railed gas block with a foreward handguard mount on it.

However IMO, if you are going to all that trouble and expense, the low-profile gas block under a railed free-float handguard is the only way to fly.
Like the one in post #5.

rc

 

[JustinJ]

I think that you will be better off finding a free float handguard, such as the Model 1 or Magpul also makes them.

To my knowledge magpul does not make a free floating handguard.

I would definitely go with a free float though. There are countless options available so you should have no problem finding something that fits your hand.
A relatively easy option would be the Troy Alpha rail as it uses the standard barrel nut. Most free float rails require you to remove the existing barrel nut and install their proprietary which should be done with a torque wrench. With the alpha rail you just remove your muzzle device, remove the existing gas block, install a low profile gas block, install the free float handguard and then install the muzzle device.

If your gas block is held on with pins be sure to use a concave tipped punch to drive them out because if you flatten the heads they will be hell to get out.

 

[gotigers]

I agree with RC. If i was going through that trouble i would prefer a low pro gas block and a free float tube style forend.

 

[NeuseRvrRat]

you can put a handguard cap between the shoulder and a low-profile gas block

but idk where you'll mount your front sight

 

[rcmodel]

But if he does that, he will still have carbine length handguards.

Which is his reason for wanting to change them to something much longer.

rc

 

[NeuseRvrRat]

Call me crazy, but I actually want a rifle length, not a mid length handguard, and would like to stay with Magpul because I like the MOE handguard I have on it currently.

i took this to mean that he wants rifle length MOE handguards over his carbine length gas system.

edit: nvm i see what you're saying now. he doesn't have a shoulder to hold the handguard cap at the rifle length. sorry

 

[bgrav321]

Ok maybe I'm a little confused, but I don't think so.

I don't want a front sight that is fixed. I want a flip up front sight that would hypothetically attach to a rail on top of my MOE rifle length handguard that I was hypothetically going to install OVER my carbine gas system, and I just basically needed a way to attach it on the muzzle end of the barrel WITHOUT a free float system, as the MOE is not a free floater.

That said, you all have neatly opened up a few more questions. A common concern I have heard about the rails, especially a rifle length, is weight. This was one of the benefits of the MOE handguard I really liked. It was light, and I could mount a light and forward pistol grip without paying the weight price of aluminum all over my barrel. I don't need 4 indivual foot long rails on 4 sides of my gun. No lasers, no grenade launchers
Flashlight and pistol grip, and eventually maybe a bipod replacing the pistol grip. Maybe.

Added to that, the MOE is very affordable. I paid 28 bucks for the one I have now. Most rails, especially a high end one, cost much more. You guys know of one lightweight and under 60 bucks? If I'm living in fantasy land that's ok, just tell me... no Leapers and no UTG and no NCStar. I don't like airsoft stuff on real guns

 

[NeuseRvrRat]

i would not mount a front sight on a handguard that wasn't free-floated. i doubt it would hold zero.

can you even put a top rail on a MOE handguard?

 

[rcmodel]

O.K.
You are living in fantasy land.

Now that that is over.

As I understand it:
What you want is a longer hand-guard with a flip-up BUS front sight.

As already covered, there is no way to do that without changing barrels to get a rifle length gas system.

Or using a low-profile gas block on your carbine barrel, under a free-float hand-guard of whatever length you want, with a flip-up BUS attached to the rail on it..

And no, they aren't $60 bucks.

rc

 

[NeuseRvrRat]

how about something like this? the flip-up is built into the sight.

here's the view under the handguard. rifle length MOE handguards would snap right on.

 

[bgrav321]

That looks good...so where to find a gas block with a flip up sight?

 

[Walkalong]

so where to find a gas block with a flip up sight?

In NeuseRvRat's pic the gas block has the tube coming out of it. It has to stay right there.

The front flip up sight with the cup to hold the rifle length hand guard is a clamp on.

Looks like what you want.

 

[skywalkrNCSU]

Why would you not want to just get a free float rail and flip up iron sight?

You can get plenty of low profile gas blocks, I have a couple (Troy and YH) but honestly, I like the the front sight post I grinded down the most. That sucker isn't moving one bit and you don't have to worry about it not being on perfect since it is pinned to the barrel.

EDIT: never mind, makes more sense with recent posts

 

[fatcat4620]

Why would you not want to just get a free float rail and flip up iron sight?

You can get plenty of low profile gas blocks, I have a couple (Troy and YH) but honestly, I like the the front sight post I grinded down the most. That sucker isn't moving one bit and you don't have to worry about it not being on perfect since it is pinned to the barrel.

EDIT: never mind, makes more sense with recent posts

Because he wants to use a MOE handguard...

 

[bgrav321]

Thanks all very much, this was definitely educational. Given me more to think about and I think I'll think some more before I decide what to do. The flip up gas blocks are almost as much as a free floating handguard lol. Might just go with a free float after all. Thanks again everyone!

BG