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Discussion Starter · #1 · (Edited)
Bare w me, I'm a bit new to AR's!

I just got a Colt MT6601 (2009 make), 20" Heavy Barrel w fixed carry handle and front sight. I want to put an after market handguard on it. I don't mind keeping the front sight on and staying w iron sights for now. Obviously, if I went w optics I would have to mount them on the carry handle or go w a red dot or something in front of it. But if I do that won't be until later.

As far as the handguard is concerned, how long of one can I get? The total length between the front sight post and edge of the upper just including that ring (not sure what thats called) that goes around the barrel is, is 12.75". If I left the iron sights as is and put an after market handguard on do I leave that ring there or does it come off? If not a 12" handguard may not fit and I would be between sizes so to speak as they usually go from 10" to 12". Should I, or do I have to, get rid of the front sight altogether? Shave it off or get a new gas block? Also, I'm not sure if this is a free floating barrel (would guess its not) so I'm not sure what type of handguard I need to buy. I like the Daniel Defense Modular Float Rail at 12". I don't need a full length quad rail, just the ability to screw on some small sections.

Anyways, I know this is a lot but any help would be appreciated, thanks very much.
 

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Discussion Starter · #2 ·
I think I figured it out. The "barrel nut" as its called comes off and a new one is put on w the new hand rail—so I can install one that is 12". It also sounds like I can add a free-float rail to my gun. But I dont know if that would help in a anyway compared to the stock setup. Any thoughts?
 

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One of the easiest that is also nice lookiing is the Magpul MOE handguard. It will fit in place of the original without having to remove the FSB or change to a free float set up and you can add what ever length of rail you want and pretty where you want. You have a standard length rifle set up. Any rifle length hand guard that fits in the standard fashion will work. If you want to go with free floated barrel it will require getting rid of the front site base and replacing with either a railed or low profile gas block and also replacing the barrel nut as the one for free floated barrel is threaded to accept the handguard.
 

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Discussion Starter · #4 ·
Ok that makes sense. Simplest way would be to get a two piece drop-in setup and throw it on in place of the old handguard. But could you remove the front sight and put a free floating one piece handguard on after replacing the barrel nut w a threaded one? Then replace the front sight again? That should at least keep any handguard pressure from affecting the barrel—but maybe I'm missing something...
 

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Just my .02$..
If its a standard length gas system it will actually fit a lot of free float handguards and still KEEP your front sight base. I personally like the front sight base with a longer free float handguard. Gives you longer sight radius and more durable front sight. Look ip bushmaster dissipator.
 

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Just my .02$..
If its a standard length gas system it will actually fit a lot of free float handguards and still KEEP your front sight base. I personally like the front sight base with a longer free float handguard. Gives you longer sight radius and more durable front sight. Look ip bushmaster dissipator.
The FSB on the dissipater is a sight only. It is not a gas block. The dissipater uses a low profile gas block hidden under the handguard.
 

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Discussion Starter · #8 ·
The FSB on the dissipater is a sight only. It is not a gas block. The dissipater uses a low profile gas block hidden under the handguard.
I was wondering about that and am obviously still learning so I appreciate everyones expertise. So my question would be: What's the difference between a dissipator and a gas block? Could I still use the front sight post w the dissipator after installing a free float tube? My goal is to make this as accurate as possible but would rather not have to purchase a new gas block and new front site if possible. But if thats the best way to go then I'll do it.
 

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Free float

In order to install a free float tube you must:(1) remove flash hider,(2) remove FSA with gas tube,(3) remove barrel nut and delta ring assy., The choice of gas block/ front sight are many, I would recommend a Yankee Hill clamp on combination gas block/ flip up front sight. If you don't do "magdumps" then the Hogue free float tube is a good setup but you MUST use a strap wrench to tighten and align the lock nut holes so the gas tube slips into the upper receiver and the bolt carrier group gas key will slip into the gas key. I did this exact same thing to a 20" rifle set up. Very tight groups with the Hornady 75grn OTHP. Fell free to contact me for any help..."I build 'em for fun and profit"
 

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Discussion Starter · #10 ·
In order to install a free float tube you must:(1) remove flash hider,(2) remove FSA with gas tube,(3) remove barrel nut and delta ring assy., The choice of gas block/ front sight are many, I would recommend a Yankee Hill clamp on combination gas block/ flip up front sight. If you don't do "magdumps" then the Hogue free float tube is a good setup but you MUST use a strap wrench to tighten and align the lock nut holes so the gas tube slips into the upper receiver and the bolt carrier group gas key will slip into the gas key. I did this exact same thing to a 20" rifle set up. Very tight groups with the Hornady 75grn OTHP. Fell free to contact me for any help..."I build 'em for fun and profit"
Thanks a lot. I didn't know they made gas blocks front sites together..will look into that. How do magdumps affect that float tube? Gets too hot not being ventilated well?
 

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On your standard Military style AR, the gas block is incorporated into the front sight base. If you remove your hand guards you will see where the gas tube fits into the rear of the fsb/gas block. On a dissipator model they hide a low profile gas block under the hand guard and then use a fake or dummy FSB out front to act as the sight only and to hold the retaiiner ring if two piece handguards are still being used. As for the hogue free float tube, it is coated in rubber so if you get it too hot, it could deform the rubber coating.
The Colt Match models are known to be quite accurate out of the box. You may want to do some shooting before you decide to change anything. It will also be worth more for resale if left in factory stock condition. I don't know if that is any concern to you and it is your call. If It were me I would probably go with a free floated hand guard and a railed gas block so you can mount or dismount a front sight to the block, and save the original pieces just in case you ever wanted to sell it, you could put it back to stock condition. Just to do that minor job you will need to purchase some tools like an armorers wrench for the barrel nut, a vise holding block for the upper so you don't break the casting trying to remove or install the barrel nut, some pin punches and of course a good vise to hold it in.
Here is a picture of a dissipator style with hand guards removed.
 

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Discussion Starter · #12 · (Edited)
On your standard Military style AR, the gas block is incorporated into the front sight base. If you remove your hand guards you will see where the gas tube fits into the rear of the fsb/gas block. On a dissipator model they hide a low profile gas block under the hand guard and then use a fake or dummy FSB out front to act as the sight only and to hold the retaiiner ring if two piece handguards are still being used. As for the hogue free float tube, it is coated in rubber so if you get it too hot, it could deform the rubber coating.
The Colt Match models are known to be quite accurate out of the box. You may want to do some shooting before you decide to change anything. It will also be worth more for resale if left in factory stock condition. I don't know if that is any concern to you and it is your call. If It were me I would probably go with a free floated hand guard and a railed gas block so you can mount or dismount a front sight to the block, and save the original pieces just in case you ever wanted to sell it, you could put it back to stock condition. Just to do that minor job you will need to purchase some tools like an armorers wrench for the barrel nut, a vise holding block for the upper so you don't break the casting trying to remove or install the barrel nut, some pin punches and of course a good vise to hold it in.
Here is a picture of a dissipator style with hand guards removed.
Ok good...I definitely have a better handle now on what my options are. I will shoot it first before I do anything. The gun will still probably shoot better than I can. I may have to bite the bullet (pun intended) and buy some ridiculously priced 5.56 ammo soon. That was another question actually. The barrel is marked 5.56 while the lower is marked .223. I know it will take both but will I get better performance out of 5.56? I've heard different opinions on that.
 

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I doubt that 5.56x45 would perform better than any good .223 ammo. I mostly hand load so I work up the load that shoots best for my rifle. With almost any gun, you have to find the round that shoots best in that particular gun, even two identical rifles from the same manufacturer could prefer different loads. It's all a big crap shoot really.
 

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Endless Handguard Options!

I wouldn't worry too much about cooling with a tube type free float handguard
RIGGLER, as they are pretty much open on both ends anyway.

Yea, like your going to find enough ammo to get the barrel hot...

I just hacked off the post on my front sight and left the lower gas block portion, because the post was blocking some of my scope view and Mr. Impatience here wasn't about to wait for a replacement gas block to be shipped. :rolleyes:

Then I decided on a mid-legnth tube for a cleaner look, but the original (complete) sight had enough clearence with that vented proper legnth tube handguard.

Keep asking any questions you might have because folks here are always willing to help out new AR owners. :cool:

That dissipator barrel set-up looks pretty cool woodstock.









 

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One of the easiest that is also nice lookiing is the Magpul MOE handguard. It will fit in place of the original without having to remove the FSB or change to a free float set up and you can add what ever length of rail you want and pretty where you want. You have a standard length rifle set up. Any rifle length hand guard that fits in the standard fashion will work. If you want to go with free floated barrel it will require getting rid of the front site base and replacing with either a railed or low profile gas block and also replacing the barrel nut as the one for free floated barrel is threaded to accept the handguard.
On the magpull handguards... Are they pretty secure? No wiggle? And can i put rails on them for handle/flashlight/optics or whatever?
 
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