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4/14/2012 3:04:02 PM EDT
How far should the gas block be located off the shoulder for proper alignment?
4/14/2012 3:07:08 PM EDT
[#1]
It should be tight up against the shoulder if you have a handguard cap, or 0.020" off the shoulder if you do not.

In any case, the hole in the gas block should be large enough to make such precise placement unnecessary.
4/14/2012 3:16:51 PM EDT
[#2]
Easy way to see is to just rotate the gas block 180 degrees and look at the gas port through the hole in the bottom of the block.
4/14/2012 3:20:08 PM EDT
[#3]
Exactly what I was looking for. No handguard cap but the hole in the Troy LPGB is large.I was thinking about putting an .020 shim behind it (thanks for the spec) just to make sure it doesnt back up.
4/14/2012 4:08:18 PM EDT
[#4]
1.  Use a small steel ruler and measure the distance from the shoulder of your barrel forward to the rear edge of the gas port.  
2.  Measure from the rear edge of your gas block forward to rear edge of the drilled gas port hole inside the bore of  the block.  
3.  The difference between the two measurements is how far you need to space the gas block forward of the shoulder of the barrel when you install it.  This will assure that the center of both holes are aligned.
4/14/2012 4:14:37 PM EDT
[#5]
Quoted:
1.  Use a small steel ruler and measure the distance from the shoulder of your barrel forward to the rear edge of the gas port.  
2.  Measure from the rear edge of your gas block forward to rear edge of the drilled gas port hole inside the bore of  the block.  
3.  The difference between the two measurements is how far you need to space the gas block forward of the shoulder of the barrel when you install it.  This will assure that the center of both holes are aligned.

I would measure it as well.
You could also use a compass (or caliper) for the measuring tool.

4/14/2012 4:48:12 PM EDT
[#6]
Quoted:
Exactly what I was looking for. No handguard cap but the hole in the Troy LPGB is large.I was thinking about putting an .020 shim behind it (thanks for the spec) just to make sure it doesnt back up.


That number does not come from a spec, but it is what I recall from measuring a couple caps.
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