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12/20/2015 6:42:39 PM EDT
Finally got all my parts in and now I have a few questions.
1. Should I install the gas tube in the gas block before installing the gas block on the barrel? or install the gas block, then the gas tube then the barrel into the receiver?
2. How do i safely and properly install my gas block? I have a vltor .750 clamp on gas block. Should I pry it apart a little or what? It is very tight on the barrel and I didn't want to force it and scratch the barrel. Any suggestions? I know I didn't describe it well, but someone out there knows what I mean.
3. Is there an easy way to install the gas tube into the gas block? How have people done it before?
Any other advice is greatly appreciated. Thank you
12/21/2015 12:08:47 PM EDT
[#1]
I've always installed the tube on the gas block first.  Put the gas block in a vise (tape up the jaws if your worried about scratches), insert/line up the tube and tap in the roll pin.

I wouldn't pry open the gas block if it is hard to push on the barrel.  You might kink it out of round and it would never seal good.  A little oil and a few taps with a mallet go a long way.
12/21/2015 5:46:00 PM EDT
[#2]
I don’t use Vltor, but I install the gas tube first in my clamp ons.
I can’t see prying it apart a little hurting, but you are the guy on the spot.
12/21/2015 5:51:35 PM EDT
[#3]
Yes, it can be a tight fit.  If possible, try reversing the screws with a thin piece of metal inside the block so as the screws when you tighten spread the block slightly.  You only need a couple of thou's.  A small metal ruler will work as the surface to which the screws will touch.  Hope this makes sense.
12/21/2015 5:55:34 PM EDT
[#4]
Also, double check the gas port location.  If you push the block all the way to the stop, it may be too far.  Remember, some barrel makers account for the fore grip cap, about 0.030 ".  You may need to keep the block a bit off the stop.  Just double check the hole locations so they line up well.  Tube installation is a matter of preference, once properly set (with Rocksett - heat impermeable), the gas block will not move.
12/22/2015 11:14:50 AM EDT
[#5]
Quoted:
Finally got all my parts in and now I have a few questions.
1. Should I install the gas tube in the gas block before installing the gas block on the barrel? or install the gas block, then the gas tube then the barrel into the receiver?
2. How do i safely and properly install my gas block? I have a vltor .750 clamp on gas block. Should I pry it apart a little or what? It is very tight on the barrel and I didn't want to force it and scratch the barrel. Any suggestions? I know I didn't describe it well, but someone out there knows what I mean.
3. Is there an easy way to install the gas tube into the gas block? How have people done it before?
Any other advice is greatly appreciated. Thank you
View Quote
jwz:  Yes, install the tube on the block as a first step.  The tiny little roll pin is a PITA, but it helps if you have a "roll pin starter punch" of the right size.  These have a little pocket in the tip to hold the pin with a dab of grease while you get it started with a small mallet.  Then drive it home with a "roll pin driver punch" that has a little tit on the end to keep the pin from getting distorted.  Far and away the trickiest part of building an AR.  Find something on your workbench to nestle the gas block in while you hammer on the pin, some people make a fixture for this, but I've always improvised.

The Vltor and YHM clamp on, low pro gas blocks work very well and will not move once installed with a drop of blue threadlocker on the screws.  My practice is to put a screwdriver tip into the little slot and pry it apart when sliding over the .750" diameter  journal and adjusting the position.  Many barrels leave about .025" clearance between the gas block and the shoulder behind the journal for a GI handguard end cap.  Some gas block makers include a little washer to take up that space.  You can leave a little gap if necessary, just be sure to measure the amount of space between the port and the shoulder to compare with the corresponding dimension on the gas block.  You can easily get the angular position aligned with top dead center by eyeballing it. Be aware these clamp on models may not clear the inside of the smallest diameter FF handguards.  good luck - CW

http://www.brownells.com/gunsmith-tools-supplies/general-gunsmith-tools/punches/gas-block-roll-pin-punch-kit-prod70048.aspx
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