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1/16/2020 9:48:49 PM
Posted: 9/14/2009 12:57:07 PM EST
so I just got my gas block and have installed it on the barrel by placing that forearm ring on and the gas block right behind it, very snug to the barrel stop, is there a way to know i didn't go back to far or something? I got it straight but, don't want a KB on my first mag
Link Posted: 9/14/2009 1:03:44 PM EST
The port on the gas block is oversized by a bit so more than likely you have it right, however my gas block did come with a very thin spacer to go in front of the barrel stop. Many people say that it should not be RIGHT up against the stop, but a mm or two in front of it.
Link Posted: 9/14/2009 1:17:38 PM EST
I'm not totally sure what you mean.
Go to here: Assemble your own LOWER, UPPER, FREE FLOAT, TRIGGER, GAS BLOCK - Step by step instructions!
and scroll down until you get to Changing your own AR15 barrel for dummies, be sure to read question 2 below that about the torque value for the barrel nut.

Haha! I'm an idiot, after reading your post again I see what you are asking.
Once you have the gas block installed but the barrel is off of the upper reciever you can blow air into the barrel while covering one end with your hand and feeling for air coming out of the gas tube with the other hand. If you can feel air coming out it's lined up.
Link Posted: 9/15/2009 6:15:59 AM EST
your method makes no sense, if the gas block is installed on the barrel, and the barrel isnt on the gun, how do you suggest putting teh barrel nut on? lol, my barrel has already been tightened down.

I have thought of 2 methods, which one is more proper?

1. gasblock with handguard cap snug against barrel shoulder.
2. gas block screws lined up with original FSB taper grooves.

its teh Daniel defense block, designed to cover FSB scars
Link Posted: 9/15/2009 6:35:01 AM EST
Measure with calipers the distance from the gas block hole to the stop.

Now take a toothpick and use it to get the distance of the gas block hole in the gas block to the very end of the gas block. Measure that distance on the toothpick with the calipers.

the difference between these two is how far off the stop you should be. I've generally found it to be the thickness of the front handguard cap which is normally installed with a FSB, but your mileage could easily vary.

If you are a smoker or know one, blow some smoke into the business end of the barrel, if your gas block is set, there should be no problem in seeing smoke come out of the hole for the gas tube AND the barrel chamber in the receiver.
Link Posted: 9/15/2009 6:36:52 AM EST
Originally Posted By cyberhedz:
your method makes no sense, if the gas block is installed on the barrel, and the barrel isnt on the gun, how do you suggest putting teh barrel nut on? lol, my barrel has already been tightened down.

I have thought of 2 methods, which one is more proper?

1. gasblock with handguard cap snug against barrel shoulder.
2. gas block screws lined up with original FSB taper grooves.

its teh Daniel defense block, designed to cover FSB scars


1 sounds like the better method, if you must use 1 of those 2. I don't have any experience matching up original taper grooves with gas block screws... my gas block did not have the screws in the same place as the FSB taper pins (CMMG low profile block was my replacement for the FSB)
Link Posted: 9/15/2009 6:52:36 AM EST
I didn't even think about using calipers, thanks!!!, just gotta wait for that midway order to get here ;)
Link Posted: 9/15/2009 12:17:48 PM EST
You can check it if you like, but my guess is that you should have nothing to worry aboiut.

The gas port is not just drilled at random, the distance from the step to the port is a well-established dimension.

DD would have access to all these specs and would know where to drill their block to line up with the gas port.

As long as the new block is installed the same as the original FSB (handguard cap against the step, block against the cap) you should be GTG.
Link Posted: 9/16/2009 1:09:25 PM EST
[Last Edit: 9/16/2009 1:15:34 PM EST by Hexahydro]
disregard
Link Posted: 9/17/2009 9:40:09 AM EST
well, i fI just leave it, what are teh effects if the hole is NOT lined up? how will the gun act?
Link Posted: 9/17/2009 3:27:09 PM EST
[Last Edit: 9/17/2009 3:28:01 PM EST by smoketheresfire]
I don't think anything catastrophic. You may not have enough gas pressure to cycle the action, resulting in a rifle that shoots single shot or short strokes. At worst I think you may have a stovepipe (shell doesn't fully clear the ejection port). No biggie. The first time I shot my build I took my tool kit along just in case I had to make some adjustments to the gas block.
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