Dimpling AR Barrel

[FrankD]

I am in the process of getting all my bits and pieces together for my next AR build and the gas block I want to use is a set screw type and my barrel is not dimpled.  I planned on getting the SLR rifleworks or KAW dimpling jig, but was curious if anyone had luck using a set screw GB without dimpling the barrel?

[TGO David]

I bought the SLR Rifleworks jig and used it to dimple the Ballistics Advantage barrel on my recent .300BLK build.  I wouldn't trust using set screws without the barrel being dimpled.

What's the brand and model of the barrel you are using?

 

[mikegideon]

11 minutes ago, TGO David said:

I bought the SLR Rifleworks jig and used it to dimple the Ballistics Advantage barrel on my recent .300BLK build.  I wouldn't trust using set screws without the barrel being dimpled.

What's the brand and model of the barrel you are using?

 

I just installed a Ballistics Advantage Premium barrel and it came with a pinned lopro gas block. It has a roll pin that's installed like the pins in an A2 sight. I will most likely buy that jig. 

https://brdengineering.com/t/gas-block-drilling-jigs

 

Edited May 10, 2019 by mikegideon

[FrankD]

I've got a faxon match series gunner barrel and a superlative arms GB.

[TGO David]

4 hours ago, FrankD said:

I've got a faxon match series gunner barrel and a superlative arms GB.

That nitrided 416-R stainless steel is going to be fun to dimple.  If you have access to a drill press, chock an end mill cutter of the appropriate size into it and use that to spot-face the dimples to get through the hardened layer.  You'll eat up a bunch of regular drill bits otherwise.

 

[FrankD]

Yeah I’m not looking forward to doing it with my bench vise and a hand drill. But the barrel should outshoot me once it’s all done

[RED333]

You can use a GOOD file to break the hard surface before you drill.

[peejman]

Start with a center drill and use some oil or other coolant.  Use the appropriate rpm for the type of drill bits you have. You don't want to get the stainless very hot. The hotter you get it, the harder it is to drill through. 

Edited May 11, 2019 by peejman

[mike_f]

I've drilled gas block dimples on 3 Faxon barrels using the SLR jigs. Two of the barrels were their "pencil" barrels with 0.625" gas block journals.

I was worried about getting through the nitride, but the bits went through it. I went really slowly because I was worried about drilling too deep. So I drilled a little & checked, a little more & checked.  I was so focused on that I didn't ready notice it being difficult getting through the nitride.

[FrankD]

Well it took a minute with my older drill bits and hand drill but I was able to get a decent enough dimple on the barrel that I am not too worried about the gas block moving.  Now just gotta do some test shots and I'll put some rocksett into the set screws and we should be good to go.