AR front sight gas block rail


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Ragnar Danneskjold
December 23, 2011, 12:25 AM
I have a Bushmaster AR-15 and I want to remove the front sight post/gas block and put a rail system on. I replaced the original heat shield hand guards with a cheap UTG quad rail that just clamps on top of the bracket under the front sight which normally holds the heat shields. But I still have the standard front sight post gas block that came with the weapon, and I want to remove that so I can add a flip up iron sight. I also want to replace that UTG quad rail with something a lot lighter and more high quality.

Is there a quad rail that has an integral gas block, so that the single piece would both replace the standard quadrail/handguard and also the gas block? Most rail gas blocks I've seen are just the small piece that would only replace the gas block, but require some other part for the hand guard. I am looking for one rail system that does all of that. Also, preferably very light weight.

Also, given what I want, this might be too much to ask, but I'm not looking to spend $300-400 dollars on just a rail. If there is something cheaper out there, I'd look at that first. I want to move beyond bottom of the barrel UTG, but I'm not the kind of guy who has thousands of dollars to drop on Troy and LaRue everything. I've been looking at Yankee Hill, but I can't see if they have a rail system that does the job I want.

Any ideas?

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NeuseRvrRat
December 23, 2011, 12:37 AM
you could cut down your current front sight base

or you could get a free float handguard and a low profile gas block or a gas block with rail on top

Ragnar Danneskjold
December 23, 2011, 12:46 AM
What would secure the free float hand guard? The rear of the current rail just fits under the Delta ring and the front fits over the handguard cap. If I took that whole assembly off the top, what holds the free float rail in place?

NeuseRvrRat
December 23, 2011, 12:53 AM
nothing holds the front of a free float hand guard. that's what makes it a free float.

watch this: http://youtu.be/rK4XzPll9U8

or any of thousands of other tutorials on youtube

ugaarguy
December 23, 2011, 01:00 AM
Your current rail system isn't free floating if it clamps to the handguard cap. Free floating rails eliminate the delta ring, and clamp to the factory bbl nut or their own supplied bbl. nut. That's that only place they touch the bbl, hence the bbl free floats from the nut forward.

The gas block, and a true free floating rail are two totally separate components. You can cut the front sight off your existing gas block, file / dremel it smooth, and then cold blue / duracoat it to make it into a low profile gas block. The Troy Industries Battle Alpha Rail free float tube is available with an integrated flip up front sight though. I hope all that helps, and if anything doesn't make sense let me know so I can try to clarify it.

Ragnar Danneskjold
December 23, 2011, 01:52 AM
I saw some videos about gas blocks, and in one someone mentioned that putting a different gas block, like a Yankee Hill low profile, on a stock barrel can cause problems since the barrel wasn't meant for that. It mentioned that even if you loctite the new gas block screws, the heat of the barrel can melt the loctite, and the gas block can shift and render the gun inop. Is this a real concern? I would prefer to replace my entire front sight assembly with a totally new gas block, as I don't want to do any cutting or makeshift mods like that. But I also don't want to have to get an entirely new barrel.

NeuseRvrRat
December 23, 2011, 01:57 AM
no.

average_shooter
December 23, 2011, 02:03 AM
You won't need a new barrel, just a free float tube and a railed gas block.

I have a DPMS single-rail gas block on my rifle. Two set screws on the bottom hold it in place. I didn't locktite them, but I haven't had any problems with the block shifting in the few years I've been using it. I just cranked the set screws pretty hard.

Free-float tubes wouldn't be free-floating if they integrated a gas block. The whole idea is that nothing touches the barrel forward of the barrel nut and transmits flex through the handguards to the barrel. So some tubes use an integrated barrel nut so the whole tube screws on and holds the barrel, and some use a nut that the free-float can be attached to. But the delta ring and forend retainer plate behind the gas block will need to go away to use a free-float system.

Ragnar Danneskjold
December 23, 2011, 02:42 AM
Free-float tubes wouldn't be free-floating if they integrated a gas block. The whole idea is that nothing touches the barrel forward of the barrel nut and transmits flex through the handguards to the barrel.

I wasn't actually looking for a free float tube in the first place thought. I still would like to find something that incorporate the entire quad rail with the gas block, if such a thing exists. This is a light weight CQB only rifle, so the marginal accuracy increase with a free float rail doesn't really matter to me. I'll get a free float if it's easier as a whole, but I'm the free float itself isn't my priority.

average_shooter
December 23, 2011, 02:54 AM
From what I understand of the AR design you'd be really hard-pressed to figure out how to get a quad rail with an integral gas block to properly align and mount without being prohibitively expensive. In all the searching I've done for gas blocks and AR parts I can't think of a single instance where I've come across anything like what you're describing.

In my opinion you're best served with a two-piece rail system and a single-rail gas block. That's going to be the easiest way to swap parts with minimal extra tool buying.

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