Set screw mismatch with barrel dimples

[Rick O'Shea]

Greetings, all.

I have a DPMS 24" bull barrel, and have purchased a Syrac adjustable gas block for it. I got the set screw version because when I removed the stock gas block it was set screwed into dimples on the barrel.
Well, guess what? The spacing of the Syrac set screws is approximately .195 longer than the DPMS block. I can tighten the screw closest to the receiver into its corresponding dimple (and the gas holes appear to line up - I measured), but the distal screw is hitting undimpled barrel.

Is it OK to just tighten it up this way?
I'm getting the barrel Cerakoted, and the people doing it are full-scale gunsmiths with a machine shop. Would it be better to have them add a dimple to match the Syrac block? I hate to spend money I don't have to, but I do want to do this right.

Any thoughts, opinions and observations are welcome.

[jtallen83]

My X-Caliber barrel only had one dimple so I just tightened the other down and haven't had an issue.

[Fletch]

Most of the dimpled-barrels I have seen only have one dimple anyhow. I would not be in the least bit concerned...as long as one of the dimples squares up with where you need your gas block to be you're good to go.

[Rick O'Shea]

OK, I feel better now.
Thanks.

 

[MikedaddyH]

Let's back this up a bit.

Have you shot this gun yet ?

Does it cycle ?

If yes ... Are you going to use a suppressor ?

If no ... Is the gas port hole lined up ?

Line up the gas port hole to the gas block and run the air can test !  Once it works ,mark spot and drill new dimple in the bottom of the barrel in the spot of the screw. Only go a fraction of an inch, VERY minimal !

 

[Rick O'Shea]

MikedaddyH,

I have not personally shot the gun, but the gentleman I bought it from test fired it a few times and said it ran perfectly. That was in its original configuration with the factory DPMS gas block.
I do not plan to use a suppressor in the near future.
I measured the distance from the gas port inside the block to the block's proximal edge, then marked a line on the barrel from its gas port of the same distance. I test fitted the gas block lining up the block edge with the mark on the barrel. When I tightened that set screw into the dimple, the block only shifted a hair.
If any drilling needs to be done, I will let my gunsmiths do it. If they have a borescope, I may have them check the gas port alignment as well.
What is the air can test? This is my first AR of any kind.

Thanks for the assistance.

 

[MikedaddyH]

Rule # 2 ...... Trust no one !!!!! Fire the gun before you modify it !!!

Once you have shot it then , change the parts you do not like. 

Since your not planning to use a suppressor then there is no real need for an adjustable gas block. It should be used as a bandaid to fix issues. If your current works please do not change it unless the handguard does not fit. The best place for your fancy new adjustable gas block is in your spare parts box waiting for the next build !

As far as the air can test , SS and I have gone over this several times . please do a search in this forum.

Edited July 19, 2016 by MikedaddyH

[Rick O'Shea]

I did a search for air can test. I found four entries, two in this thread. The other two indicated that the test consisted of shooting pressurized air into the gas system to see if it will push out a piece of brass placed in the chamber. This would rule out a complete blockage but not a partial one.

I currently have no location available to fire the rifle. That will change soon, but in the meantime I'm changing the configuration to match my preferences regarding the feel and look of the gun. I wanted a long handguard. This dictated changing to a low-profile gas block. I reload, and will be tweaking loads for the gun. I prefer the flexibility that an adjustable block offers.

[MikedaddyH]

19 minutes ago, Rick O'Shea said:

I did a search for air can test. I found four entries, two in this thread. The other two indicated that the test consisted of shooting pressurized air into the gas system to see if it will push out a piece of brass placed in the chamber. This would rule out a complete blockage but not a partial one.

I currently have no location available to fire the rifle. That will change soon, but in the meantime I'm changing the configuration to match my preferences regarding the feel and look of the gun. I wanted a long handguard. This dictated changing to a low-profile gas block. I reload, and will be tweaking loads for the gun. I prefer the flexibility that an adjustable block offers.

What is the diameter of the gas block ?

What is the inside diameter of your new handguard ?

 

[Rick O'Shea]

It will fit.
Gas block total height is 1.572".
Handguard ID is 1.75"

All this was checked before I ordered either one.
Why do you ask?

[MikedaddyH]

If its not broke, don't fix it. Try your new handguard setup before you change to the new gas block. If it works don't put the new gas block on.

[blue109]

On 7/19/2016 at 0:40 AM, MikedaddyH said:

Rule # 2 ...... Trust no one !!!!! Fire the gun before you modify it

This. This. This. Get that gun out as factory as you can.