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4/6/2017 3:50:50 PM EDT
Are low profile gas blocks, specifically Odin Work's, designed to be but up against the fatter part of the barrel?  I know that when using a traditional GB you have to have it offset a little bit for it to get the right amount of clearance for gas to get into the tube.

Hopefully I am going to get to put my upper together in a couple weeks and I want to go ahead and try asking the questions I can think of.

Thanks guys!
4/6/2017 3:56:24 PM EDT
[#1]
Yes, tight against the barrel.
4/6/2017 4:02:37 PM EDT
[#2]
Thank you!  After posting this I went to youtube and apparently 2 weeks ago they put up a video answering it too.  Thanks again.
4/7/2017 9:33:00 AM EDT
[#3]
Quoted:
Are low profile gas blocks, specifically Odin Work's, designed to be but up against the fatter part of the barrel?  I know that when using a traditional GB you have to have it offset a little bit for it to get the right amount of clearance for gas to get into the tube.

Hopefully I am going to get to put my upper together in a couple weeks and I want to go ahead and try asking the questions I can think of.

Thanks guys!
View Quote
Shinji:  It depends on the barrel.  Many are made to fit GI front sight/gas block combos, with the little sheet metal handguard end cap (about .020" thick) sandwiched inbetween the block and the "fat part" of the barrel behind the journal.  Others barrels are made for a lo pro block to butt right up against that fat part.  

If you are using a gas block which has the little set screws on the bottom and your barrel has a dimple opposite the gas port, then just put the rear set screw into that dimple and you are ready to go regardless. Otherwise, measure the distances on the barrel and the gas block to find out where to place the block. good luck - CW
4/7/2017 2:48:56 PM EDT
[#4]
Good point Chasw, I am specing this: Bravo Company Manufacturing 16" M4 Barrel, Stripped in case you or anyone knows.

Thanks again,

Shinji
4/7/2017 8:52:27 PM EDT
[#5]
It depends on both the barrel and the block.

A standard dimension barrel and a standard dimension block will require a gap between the handguard retainer shoulder and the gas block.

Some barrels (like Larue) offset the retaining ring foreward, such that it won't work with a handguard ring anymore, so that gas blocks fit against the shoulder.

Some gas blocks (like at least some YHM) are made such that they fit up against the shoulder with a barrel with a standard dimension.

Using such modified barrel and modified gas block together will obviously not work.

The easy way to check your particular parts is before you install the gas tube into the block, to just put the block on the barrel upside down and look at the gas port through the hole in the bottom of the block. Center the gas port in the hole, that's how far it needs to sit off the shoulder on that particular barrel. If it's a set screw type block, you will have to remove the rear set screw to look through the hole.
4/8/2017 5:43:07 AM EDT
[#6]
Thanks for the tip Gamma.  This will come in handy.
4/9/2017 12:52:40 PM EDT
[#7]
A method I've used successfully is to first make myself an alignment dowel by chucking a round toothpick into a screw gun and sanding it so that it's a slip (but not sloppy) fit in the gas port.  Then insert the dowel into the barrel and cut it off flush with the outer barrel surface.  Remove it and mark the dowel in the middle and cut a notch around it there with a sharp knife (where it will break later on).  Lay the barrel so the port is horizontal and the dowel is flush with the outer surface.  Put on your gas block and then use a cleaning rod to push the dowel into the port on the gas block and wiggle the block as necessary for the dowel to go into it and it's centered on the barrel.  Turn the barrel port vertical so that the dowel falls down into the barrel and break it at the notch with a cleaning rod. Then remove both parts of the dowel and you're done.
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