Need some AR help from someone who knows

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TonyAngel

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Man, I’ve got the new gun bug bad.

I was getting ready to pull the trigger on a 10.5 upper. Now I’m wondering about something.

I’m sure that you guys are familiar with the Dissipator. What I want to do is get a pistol upper with a carbine gas system but install a clamp on front sight so that I can run mid length hand guards. I don’t want to free float. I want to use MOEs.

How long does the barrel need to be to do this? If it’s much longer than 11.5, I’m gonna scrap the idea.
 
This image might give you an approximate.

ar-15-gas-length-e1495753152529.jpg

I count about 11.5" to the front of the A2 sight post. Then add 0.6" for the threads for the flash hider. You might be able to save 1/4" by grinding off the bayonet lug. I think if you used a short, non A2 front sight an 11.5" barrel would probably work.
 
Thanks a lot bassjam. From the pic it looks like it’s gonna be close but doable. I’m gonna hack/grind that A2 down to nothing but a gas block.
 
TonyAngel said:
Thanks a lot bassjam. From the pic it looks like it’s gonna be close but doable. I’m gonna hack/grind that A2 down to nothing but a gas block.
Click to expand...
If you are not going to use the sight post itself, but just use it as a front retaining ring pin, you could use a clamp-on or set-screw gas block, and cut it in half, if needed.
 
badkarmamib said:
If you are not going to use the sight post itself, but just use it as a front retaining ring pin, you could use a clamp-on or set-screw gas block, and cut it in half, if needed.
Click to expand...

If I go with something like that, I could do it with a 10.5 barrel.
 
TonyAngel said:
If I go with something like that, I could do it with a 10.5 barrel.
Click to expand...
Looking at the pictures provided by @bassjam , I see a potential issue. I know they make dissies using rifle-length handguards on carbine and mid-length gas systems. From what I see, you would DEFINITELY have to cut the Lo-Pro gas block down, so that the front of it isn't keeping the front of the drop-in handguard from closing. If you look at the carbine and mid-length gas systems in the picture, you will see where the mid-length handguard cap would interfere with a carbine-system gas block. A mid-length handguard would still need about 3/8" of clearance behind that, at least.
 
TonyAngel said:
Man, I’ve got the new gun bug bad.

I was getting ready to pull the trigger on a 10.5 upper. Now I’m wondering about something.

I’m sure that you guys are familiar with the Dissipator. What I want to do is get a pistol upper with a carbine gas system but install a clamp on front sight so that I can run mid length hand guards. I don’t want to free float. I want to use MOEs.

How long does the barrel need to be to do this? If it’s much longer than 11.5, I’m gonna scrap the idea.
Click to expand...
You're over thinking the whole project. If you look carefully at the middy and carbine, you'll see that the cap on the middy is about where the front of the FSB is on the carbine.

The goal isn't to install a standard middy handguard on an 11.5" it's to install a handguard that's the same length as a standard middy without going free float. Magpul MOE handguards won't work, but their Slimline handguards will.

Slimline handguards will cover the upper all the way up to the front of the FSB. They're slim, rugged, lock in tight and do an excellent job protecting your hands from heat. I use Magpul Slimlines on my shorties and like them better than any other drop in handguard I've tried.

Mission First Tactical also offers a set of drop in handguards similar to the Slimlines, but I've only seen them in a catalog.

Get the Slimlines or the MF handguards and simplify your life.
 
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MistWolf said:
You're over thinking the whole project. If you look carefully at the middy and carbine, you'll see that the cap on the middy is about where the front of the FSB is on the carbine.

The goal isn't to install a standard middy handguard on an 11.5" it's to install a handguard that's the same length as a standard middy without going free float. Magpul MOE handguards won't work, but their Slimline handguards will.

Slimline handguards will cover the upper all the easy up to the front of the FSB. They're slim, rugged, lock in tight and do an excellent job protecting your hands from heat. I use Magpul Slimlines on my shorties and like them better than any other drop in handguard I've tried.

Mission First Tactical also offers a set of drop in handguards similar to the Slimlines, but I've only seen them in a catalog.

Get the Slimlines or the MF handguards and simplify your life.
Click to expand...

THANK YOU. And this is why I posed the question. I had no idea those even existed. Man, I've gotta start reading the gun mags again. Apparently, I've missed a lot.
 
Nah, just hang out in the right forums, asking the right questions

Colt 6933 (11.5 inch barrel) with Slimline handguards & buttstock
i-RnKB7QM-L.jpg

Colt 6933 with factory original furniture
i-dWJHWFJ-L.jpg

My first AR pistol. 10.5" barrel with MOE handguards and the original SB arm brace
i-RKLwL49-L.jpg
 
Go free float, make your handguard as long as you want it to be - can even be longer than your barrel, as long as you have a suppressor or linear compensator to bring the blast out front before release.
 
Is there a reason you dont want to get a free float rail? There are several good ones that connect to the standard barrel nut.
 
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Free float handguards are more expensive and I don't think they offer much advantage for a shorty upper
 
They don’t have to be more expensive... I did something similar (faux dissipator pistol) for the better sight radius On a 10.5” blackout:
A2 front sight. Cut off b. Lug. Drilled, tapped, slotted to make it clamp on. Low profile gas block under the rail (pistol length gas) . Then took a $20 rail and notched out the top for the front sight.
EC3F8BFD-AE99-4BD6-96E7-A1256646BF64.jpeg 9318F98F-1EF5-432D-9054-0B905E40B249.jpeg
 
I want to go with MOE furniture and keep it light. I want it as light as possible. Besides, I don't like the way the new generation of tacticool handguards feel. I find them uncomfortable and by the time you add all of the covers to make it comfortable, it's FAT. My 14.5" goto AR is free floated and even on that I went with a straight aluminum tube for comfort and to keep it slim. I just drilled and tapped for rail sections where I needed them.

I still can't believe that I actually expended thought on this and MagPul had the answer sitting there.
 
TonyAngel said:
I don't like the way the new generation of tacticool handguards feel. I find them uncomfortable and by the time you add all of the covers to make it comfortable, it's FAT.
Click to expand...

I think you’re confusing the “new generation” with the “last generation.” The current common theme, for a decade or so now, has been Mlok and keymod handguards, leaning towards slim rails for the very reason you describe. Nobody liked quad rails, so we came out with modular systems. Nobody liked fat rails, so we came out with slimline handguards.

The Midwest industries G3, as an example, of what has become typical of the “current generation” of handguards.
 
Varminterror said:
I think you’re confusing the “new generation” with the “last generation.” The current common theme, for a decade or so now, has been Mlok and keymod handguards, leaning towards slim rails for the very reason you describe. Nobody liked quad rails, so we came out with modular systems. Nobody liked fat rails, so we came out with slimline handguards.

The Midwest industries G3, as an example, of what has become typical of the “current generation” of handguards.
Click to expand...

No, I'm not confused. I'm well aware of what the current generation of handguards are like. I built an upper for my girlfriend and she got them because she wanted them. I shot a 10.5 yesterday and an 11.5 today. Both had some flavor of Mlok's on them. I didn't like them. I know what I want. I just wasn't aware that MagPul had such a simple solution.
 
BCM offers a 12.5 cabine gas system with a clamped on front sight that would accept mid length handguards. I like the MOE SL myself.
 
Mike .45 said:
BCM offers a 12.5 cabine gas system with a clamped on front sight that would accept mid length handguards. I like the MOE SL myself.
Click to expand...

Oh, yeah. I think the MOE SL rig is going to be just what I want. Besides, 12.5 is mighty close to 14.5 and I already have one of those. lol
 
I wish Magpul would come out with the rifle hand guard in the Slim. I would love to try one on my Dissipator.
621B04F1-32A4-4597-B3D8-F132E522B40C.jpeg

And God help me it they start making furniture in MCT (Medium Coyote Tan). I would have to buy new furniture for some of my rifles or gust built some new ones.

I have two rifle builds that I need to finish, but I’m already thinking of another pistol built.
I would start with something like this. Put a FDE Slim hand guard on and coat the upper FDE.
273E9981-B69A-4F6E-9621-629528AB471C.jpeg

And finish it off with this style lower, but coat the lower FDE.
6449968D-18BA-432A-82B2-F3A3B71963A1.jpeg
 
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