Gas Block Issue… Again...

[tbass23]

Since I value everyone's experience and advice on this forum, I thought I'd ask another question regarding my gas block… Thanks in advance.

Yesterday I took my AR into a gunsmith I was referred to, to changed my aluminum gas block to a steel Midwest Industries low profile gas block. I decided to have it done "professionally" so I could install a gas block I trusted and put this behind me.

When I got the rifle back I gave it a quick look at the shop and thought it looked great. Today I decided to clean and lubricate the rifle and noticed that the gas block is canted at about a 12:30 angle. I was pretty upset that this wasn't don't correctly since I took the time and spent the money to have someone do this…

I haven't shot the rifle yet but plan on it this weekend. If it isn't 100% like before I am taking it back to get fixed. If it does run 100% with the different ammo I am bring I am wondering what everyone else would do? Would you live with the slightly canted GB? Am I just being OCD? Or should I insist the smith tears down this rifle again and fixes it?

Thanks!

T

 

[medalguy]

Chances are if the block is canted, so is the gas tube and it's probably rubbing on the bolt carrier key. Because the opening for the gas port is usually bell shaped, if it's a little out of alignment, it may fire and function but it's not correct. Take it back and have it fixed.

 

[FL-NC]

The gas hole in the barrel is pretty small, and the hole in the gas block it needs to line up with to feed into the tube isn't much bigger. Everything needs to be lined up to insure proper function and also to just be put together correctly, plus the gas tube interface into the bolt carrier already mentioned. Make him do it right, esp. if he charged you.

 

[tbass23]

update

Thanks for the responses. I took your advice and took the rifle back to the smith. The owner fixed it and it looks great. Now to the range!

T

 

[Ibmikey]

One thing a non AR mechanic does not do is allow for the handguard retainer thickness when installing block and just butts it against shoulder on barrel. Although very forgiving if not using thr retainer allow approximately 0.035 space. A gasblock is not a gunsmith project unless you are having it pinned, they are so easy to line up, mark a pencil line through the gas port and a couple inches longer--using a straight line from center of gas tube hole in upper receiver. Use this line to align tube and block, allowing for the aforementioned space. Tighten Yer dun!

 

[Taurus 617 CCW]

Chances are if the block is canted, so is the gas tube and it's probably rubbing on the bolt carrier key. Because the opening for the gas port is usually bell shaped, if it's a little out of alignment, it may fire and function but it's not correct. Take it back and have it fixed.

I used to be one of those guys who professionally installed AR parts for people so I can speak from experience from the other side of the gun counter. The gun will probably function but the job was not done right. You paid money to have a job done right and now it is his responsibility to make it right for you (at no cost to you). I have installed many low profile gas blocks and one of the last things I do before putting the handguard back on is a visual check to see if the thing is lined up. I check from the front and from the back. Lastly I do a gas flow check to make sure the gas hole in the barrel is lining up with the gas hole in the block. When everything was lined up, I red loctited the screw on the underside of the gas block. I even went so far as to spot drill a dimple in the barrel to make sure the gas block wouldn't rotate during use. Its the little things that make the difference between an okay job and an outstanding job.

 

[MistWolf]

One thing a non AR mechanic does not do is allow for the handguard retainer thickness when installing block and just butts it against shoulder on barrel. Although very forgiving if not using thr retainer allow approximately 0.035 space. A gasblock is not a gunsmith project unless you are having it pinned, they are so easy to line up, mark a pencil line through the gas port and a couple inches longer--using a straight line from center of gas tube hole in upper receiver. Use this line to align tube and block, allowing for the aforementioned space. Tighten Yer dun!

Not all gas blocks are designed to be used with a handguard retainer

 

[Blade First]

As suggested before, if you are a do-it-yourselfer, make a pencil mark behind the journal that is in alignment with the gas port. Slide the gas block on the journal and visually align it with the pencil mark. Works every time...but be sure you don't change the orientation when tightening set screws or pinch bolts.

Use the backup check, too, of eyeballing the projection of the gas tube into the upper receiver...shouldn't be canted to either side.

"Not all gas blocks are designed to be used with a handguard retainer."

Correct, but if you have removed the FSB and cap in order the use a lopro block in conjunction with a free-float tube/rail, you should account for the thickness of the cap/retainer...which is his point, I think.

Retainer thickness is just a few thousandths but enough to compromise the port if not taken into consideration.

 

[MistWolf]

Some gas blocks will be misaligned when used with a handguard retainer, or when gapped for a handguard retainer. Some gas blocks have to be pushed against the shoulder. I had to trim one low profile gas block so it would correctly align with the gas port when installed with a handguard retainer