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Adjustable gas block question?????

STI_1911_Guy

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Feb 1, 2011
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I looked on here and couldnt find any info but if i missed something please kindly point it out. But i am looking into an adjustable JP gas block and i seen on the reviews from midway usa that he said you have to drill and tap stuff. I guess before i get one how hard are they to install or how do you do it? And does it affect accuracy at all?
 
Re: Adjustable gas block question?????

I have the JP on my REPR. 3 screws clamp it on, and you need a punch for the roll pin that holds the gas tube.
 
Re: Adjustable gas block question?????

JP has excellent instructions posted online, installation is a breeze, you should have no problems.
 
Re: Adjustable gas block question?????

If I understand correctly, when you buy the block alone from JP, you will have to drill & tap the gas tube you mate to it. If you buy the block and a tube from JP as a set, you don't. That is just what I gathered from reading their website though. Maybe I am mistaken.
 
Re: Adjustable gas block question?????

What? I have two JP adjustable gas blocks on my .308 ARs. Neither one is drilled or tapped for the gas tube. The gas tube is affixed in the normal way using a roll pin.

Not sure where this came from but the block is attached with 3 cap screws that tighten the bottom of the gas block like a clamp to the barrel. As I said before the gas tube then just slides into place in the upper and into the gas block with the roll pin through the hole in the gas block and the gas tube.
 
Re: Adjustable gas block question?????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mjh</div><div class="ubbcode-body">JP has excellent instructions posted online, installation is a breeze, you should have no problems. </div></div>
I have also installed many of these and they are easier than any gas block for install!
 
Re: Adjustable gas block question?????

From the instruction sheet found at JP's website:

"...Finally, it may be necessary to run a 8-32 bottoming tap into the gas adjusting screw hole before
installing the set screw, as the screw abuts the bottom of the gas tube....."

Perhaps you guys that have installed these can enlighten the rest of us on what this means.
 
Re: Adjustable gas block question?????

yup, your right, i forgot about that. you are supposed to run a tap through the screw hole for the adjustment screw, but its not real necessary. just run the screw in all the way the first time to seat it in the gas tube and it will work just fine.
 
Re: Adjustable gas block question?????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: overkill</div><div class="ubbcode-body">yup, your right, i forgot about that. you are supposed to run a tap through the screw hole for the adjustment screw, but its not real necessary. just run the screw in all the way the first time to seat it in the gas tube and it will work just fine. </div></div>

So are you saying that the tube requires an extra hole for the set screw, implying that the screw restricts gas flow within the gas tube, or does the screw just have to butt up against the outside of the gas tube for some reason? If the former, it seems like you either have to buy a tube from JP or drill an additional hole in the tube if it did not come from JP. This is kind of what I was assuming from what I had heard previously and read on their website.
 
Re: Adjustable gas block question?????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bowslngr</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: overkill</div><div class="ubbcode-body">yup, your right, i forgot about that. you are supposed to run a tap through the screw hole for the adjustment screw, but its not real necessary. just run the screw in all the way the first time to seat it in the gas tube and it will work just fine. </div></div>

So are you saying that the tube requires an extra hole for the set screw, implying that the screw restricts gas flow within the gas tube, or does the screw just have to butt up against the outside of the gas tube for some reason? If the former, it seems like you either have to buy a tube from JP or drill an additional hole in the tube if it did not come from JP. This is kind of what I was assuming from what I had heard previously and read on their website. </div></div>

The latter is correct.
 
Re: Adjustable gas block question?????

every gas tube already has a notch cut out of the bottom of it where it goes into the gas block where the propellent gasses would normaly enter the tube from the bbl. the JP adjustable block just has it lined up so that a screw(with the same radius as the notch in the gas tube) will thread accross that opening so you can adjust how large the opening in the gas tube is.
 
Re: Adjustable gas block question?????

Not to hijack....but A.R.M.S includes 0.025" thick washers to use with their front sight/gas blocks to seat behind the gas block and in front of the barrel shoulder on a free floated barrel.

Does anybody know where to get these?

I can't find them anywhere as a spare part.