Non-dimpled Barrel and Set Screw Adj Gas Block Install - Advise

[arptsprt]

Yes, I have searched and found some good information but would like some additional advise about install of an adjustable gas block on my DD MK18 please.

Won't get into all the gory details but a Syrac adjustable gas block was installed by DD for me as part of a warranty repair agreement for a problem child MK18 I have had fits with since day one (for the record, though frustrating, DD has bent over backwards to help me and their warranty administrator has been nothing short of outstanding). I run the upper dedicated suppressed. Well, after just a couple hundred rounds after warranty repair, the upper become a single shot out of the blue yesterday. The problem? The gas block had come loose and was sliding down the barrel cutting off the gas. Here's my setup:

DD MK18 10.3 barrel
Syrac Gen II adjustable gas block - set screws
Dedicated suppressed upper - running a GemTech Trek Titanium
Apparently DD does not dimple their barrels. Found that out last night upon tear down of the upper. Further, it does not appear the block was installed using any thread locker/Loctite.

After my research, it appears as though dimpling isn't critical and resetting the block with degreased threads and red Loctite on the set screws should work.

Is there a torque spec I should use for the set screws? Is very hand tight with the red Loctite sufficient?

Long run, is just best to have the barrel dimpled? Seems the main purpose of dimples is simply timing of the block. There are clear marks on the barrel from the previous install I can repeat without the dimples.

If it is recommended I get the barrel dimpled, any recommendations on a gunsmith? We have nobody around here who can do it. I have asked. I will need to have this sent out for smithing. Pain in the arse.

Any other advice/recommendations? First time with this. Thanks.

[.46caliber]

The barrel needs to be dimpled for those set screws. It's really not a difficult operation and can be done by the end user. I can understand though if you want it professionally done to make sure it's done cleanly.

Honestly, I'm quite surprised DD didn't dimple the barrel when they installed the Syrac.

The dimples serve a larger purpose than indexing the block.

Check out the instructions Geissele includes with their GBs. Should provide some helpful info for you.

http://geissele.com/super-gas-block.html

[markm]

Dimpling at home is easy if you're handy at all hand have a drill. I just take a pointy punch and make a small starting dimple so the drill bit doesn't wander. Then I take a drill bit and start drilling away until the dimple is deep enough. Drilling on barrel steel goes pretty slow so it's not very easy to go too deep.

[BufordTJustice]

Dimple the barrel. Use McMaster Carr knurled cup tip screws. Use Resbond 907TS blue or loctite high temp red threadlocker (271 IIRC). Enjoy your repeating rifle again.

[MistWolf]

To repeat- you can dimple the barrel yourself. All the dimple needs to be is a shallow drill start. Barrel steel isn't very hard as steel goes, and it's easy to go too deep.

Use blue Loktite on the screws and stake them lightly. You can use a light coating of Never Seez or green Loktite on the barrel itself to seal the gas block against leakage. If you use Loktite on the barrel, only use the green and make sure it's made to wick

[Iraqgunz]

I'm amazed at those who still don't realize that dimpling is important.

[Laust]

Why not get it pinned?

[StainlessSlide]

Some think that a free floated handguard will protect a gas block underneath against impacts. In fact a rail provides little protection against side impacts. A side impact against the rail will be transmitted to the projecting top of the gas block with very little diminution and of course this will tend to twist the block. If the block twists the plenum and the gas port can be misaligned.

In my mind, this is the most important reason for dimpling, to provide stronger resistance against twisting.

On second thought, there would also be a forward force from the pressure in the gas tube. If we take the max gas tube pressure as 2kpsi, and the i.d. of the gas tube as .125 (iirc), the the maximum forward force would be about 24 lbs.

[Joe Mamma]

Is there a torque spec I should use for the set screws? Is very hand tight with the red Loctite sufficient?

I use a barrel with a dimple, and 33 inch-pounds of torque on the set screws with ultra high temp blue Loctite,.

Joe Mamma

[jerrysimons]

I too was curious about a torque spec. After not finding anything I settled on 30-35in-lbs and red 272 loctite after dimpling only the rear set screw location. Clint at Black River Tactical and BCM recomended to just do the rear dimple. Not all gas blocks have the same distance to center between screws, btw. Check out BRD engineering for a dimple jig