Gunsmithing Dimpling barrel for gas block screws.

[Wisconsinner]

I am trying out a different gas block on my barrel to get the lowest profile I can get. I ended up with a badger ordnance tdx gas manifold which was one of the lowest profile I could find. I temporarily put the block on my barrel and see a huge need to dimple both screws because they stick out pretty far. Badger recommends drilling a .188 wide hole .125 deep. That seems excessive to me! I feel more comfortable going .080 - .090 which would set the screws just above flush.. How deep is too deep? Any help would be awesome!

 

[E-Tool]

.125 should be ok on medium (USGI) or heavy barrel if you have a very thin profile barrel then perhaps not.

I’ve done this two barrels using a jig and a hand drill. It works, but not the best, and in hindsight I know I didn’t drill deep enough.

Unless your using a hispeed drill press I wouldn’t worry too much about going too deep. Chromoly is hard stuff.

 

[Trigger Monkey]

How deep is too deep?

Into the rifling.

If you only want to drill it .090 that'd probably still work fine.

 

[Wisconsinner]

I forgot to mention, its a .750 journal.

 

[alwaywatchyoursix]

I gotta know, is there a reason you're trying to go so low-profile that you're concerned about the length of the set screws? They tend to be pretty small things to begin with, and according to your numbers, you're only changing it by less than a tenth of an inch...

 

[Wisconsinner]

I gotta know, is there a reason you're trying to go so low-profile that you're concerned about the length of the set screws? They tend to be pretty small things to begin with, and according to your numbers, you're only changing it by less than a tenth of an inch...

I want as much clearance between the handguard, and gas block as possible. I had a BCM low profile block installed originally, which only gave me .050-.060. I wanted more than that. Hindsight I shouldn't have used such a slim rail with this build.

 

[alwaywatchyoursix]

I want as much clearance between the handguard, and gas block as possible. I had a BCM low profile block installed originally, which only gave me .050-.060. I wanted more than that. Hindsight I shouldn't have used such a slim rail with this build.

Holy crap, either your numbers are off by an order of magnitude or that really is the world's slimmest rail. Now I gotta know which one.

 

[Mike Casselton]

Spend 50c and use shorter set screws?

 

[Wisconsinner]

Holy crap, either your numbers are off by an order of magnitude or that really is the world's slimmest rail. Now I gotta know which one.

MI combat rail. And my numbers are right on.

 

[unclemoak]

I use an SLR jig because the wear parts are replaceable and it covers all the common set screw distance sizes.

Before you use the drill bit, I’ve found that using a 5/32” transfer punch to put a dimple in the barrel first helps prevent the drill bit from walking (which can make your dimples off center)

Also helps to have a bunch of new (sharp) 5/32” drill bits on hand.