First off I hope I'm posting this in the right place. Not long ago I purchased a upper that had a cycling issue. After swapping parts around I determined it was a gas issue, I removed the gas block/tube to find out that apparently this was someones DIY gone wrong. The gas port does not align with the block...and pretty much never will. When the barrel was dimpled it was done incorrectly and the two ports barley overlap. Every round fired either stovepipes or only kicks the bolt back enough to expose brass.  Now my idea for a solution is to take a Dremel and form an angel on the gas block to direct gas into the port. Will this work? Is it safe?   Thanks for the help.

There are enough good companies producing or selling qualitybarrels at the cheapest price in history. Save yourself the trouble of chasing down an issue and rigging your gun...buy a new barrel.

1. You could get a clamp type gas block and align to the gas port independent of the dimple. Then bend the gas tube to align with the barrel nut and make sure it is straight and doesn't bind with the gas key of the carrier.

2. Another way would be to enlarge the hole on the gas block so it overlaps the barrel gas port. The set screw hole in the rear of the gas block is aligned with the gas block port. You would need to use a larger drill bit and enlarge both the set screw hole and partially the gas port. Probably just 1/8" deep in the gas port. The set screw hole would need to be tapped for a larger set screw.

How much larger would the gas block port need to be enlarged to overlap the gas port on the barrel?
Do you know how large the gas port is on the barrel?
What type of gas block do you currently have?

1. would seem the be the easiest route.

The position of the set screw is the least of your worries. Regardless of the set screw, the barrel gas port hole should line up with the gas hole in the gas block if each was manufactured correctly.
If you say they will never line up, one of them was not drilled correctly concerning the positioning of the hole or the gas block shoulder machined on the barrel is not in the right position.
In what way are the holes not aligned? Will shimming between the gas block and gas block shoulder align the holes? Will removing material from the rear surface of the gas block align the gas holes.
A little repositioning of the gas block fore or aft should not impact the relationship between the end of the gas tube and BCG gas key very much.
If the gas port on the barrel is out of position radially or rotationally then that is a more difficult issue that may be solved by enlarging the hole in the gas block.

After you get the gas worked out then you can drill a set screw dimple if necessary.

How exactly do the ports not align??
Rotational or along the centerline of the barrel.
Is the gas port at TDC on the barrel?
Pictures would probably helpful.

If I understand correctly the  gas port doesn't line up longitudinally (i.e. along the long axis of the barrel.)

This, at least to me means the barrel was made f'd up to begin with, or the opening that interfaces with

the gas port on your gas block is way too small.

The front HG retainer, if installed, or not, isn't thick enough to affect this...

As stated by others, pics are worth 1000 posts.

I this a barrel someone else already dicked with?  or did it come this way from the mfg.?

as an experiment I might try to mod the GB if it was just a little off but seriously there are some great barrels out there for low prices right now.

I would just re barrel it..

Yes it could work. (modifying your gas port)  It is not unsafe.



I would fit a new gas block.

Either redo the dimple job or use a clamp on gas block if the gas port is TDC on the barrel. If its not you may still be able to use it if its
not to far off of TDC but your gas tube and block will just be twisted and would require you to use a free float tube. If all else fails make
it a .22!

You have a couple of options:
1) you could make do with what you have and try to monkey engineer it to work
2) or you could buy a new barrel and fix it properly

If it were my rifle, I'd go with option #2.  There aren't a whole lot of things where I'm meticulous, but firearms safety is one of them.  I would rather be 100% sure of my rifle than wondering every time if that shot I just fired stovepiped or didn't eject properly.  I might not fail 9 out of 10 times, but you have a 30 round magazine :-). If your luck is anything like mine, it would run perfectly... until you needed it to.  I should also add that I would never buy a motorcycle helmet at a yard sale either.

I don't really see it as a safety issue. (unless it's your go-to HD rifle)  



Personally I would probably use a clamp on block to align the port better, then bend the gas tube if needed to keep it running just fine.  Then I would put it on my bumpsaw and wear the barrel out.

It sounds like the dimple was done wrong, not the gas port. Just buy a clamp on gas block and forget the dimples.  

http://www.bravocompanyusa.com/Daniel-Defense-Clamp-Low-Profile-Gas-Block-p/dd-9091.htm

Something like that in the correct size will fix it.

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Easiest (non-bubba) route is to buy a clamp-on style gas block that doesn't use set screws.

Correct route would be to trash the mystery barrel.

No reason to trash a barrel you could burn up

I had a customer with a similar problem.  I inverted the gas block on the barrel and looked through the set screw hole on the bottom of the GB and found that the GB opening did not line up with the gas port on the barrel, it seems the GB hole had been drilled too far forward or the GB was intended to be used without a forend cap.  I chucked the GB in my mill and milled off some of the back of the GB, putting the hole closer to the port.  After a couple of tries, I had the port centered in the GB hole.  Touched up the back of the GB with blacking and fired 50 rounds of mixed ammo to test functioning. Problem fixed.