Tools for barrel dimpling for gas block

[SomeOtherGuy]

Use a hand drill, go slow, and use a little oil. For softer steel (stainless) just about any drill bit will work. For harder steel (nitride surfaces) a good sharp HSS, or better drill bit is a must to get through the hard surface.

For nitride-treated surfaces you can also just grind off the nitride layer with an aluminum oxide wheel on a Dremel tool and drill without much trouble. I used this technique for pinning a Geissele SGB and it worked great.

Be sure you have good drill bits that are sharp. If it comes from McMaster or another reputable source good, don't plan to use a Walmart or Sears consumer grade bit. I've had good luck with cobalt bits, but HSS should be fine if it's sharp and quality. TiN (titanium nitride, sometimes confusingly called "tin") can be found on both quality and junk bits, so it alone doesn't tell you if the bit is going to be good.

Dimpling with a hand drill is entirely doable if you clamp the barrel in place.

FWIW, though, most quality barrels either come dimpled, or can be found dimpled (or even with a professionally pinned gas block) if you shop around.

[Sparky5019]

BRDE makes excellent jigs that index off the gas port. They have versions specifically for most of the popular gas blocks on the market.

[markm]

There's Really no need for a jig. The first part of elephantriders post nails it.

[nightchief]

I have the BRDE jig. For those hand drilling the dimple, what are you doing to support the barrel? Also, I'm looking for some advice on drill press or small mill that can do this job and others. I have some other uses for such a tool.

NC

[26 Inf]

I have the BRDE jig. For those hand drilling the dimple, what are you doing to support the barrel? Also, I'm looking for some advice on drill press or small mill that can do this job and others. I have some other uses for such a tool.

NC

Night Chief - I use a reaction rod secured in my floor mounted vise. Not much force required with a good bit and oil.

Ref the drill press and mill - if you are buying a table top drill press make sure you place a piece of stock on the table, make contact with the chuck, and put some force on it - check to see if the is any flex. My first table top drill press worked fine as long as I was drilling soft wood, anything hard and the column allowed the head to flex, lesson learned.

Garage sales and estate auctions are sometimes good places to pick up older solid drill presses.

[Iraqgunz]

If you want to Bubba it, go for it. I recommend the proper way using a drill press and a dimpling jig.

[skimbleshanks]

A drill press isn't some runaway mechanism that once started won't stop drilling. Seems like this task may be over your head even with it being a very simple task. Drill press and jig is probably best but a punch and hand drill have probably done just as many.

[26 Inf]

Geissele seems to think a hand drill works okay, without a jig :

6. Spot drill barrel. Using a 135 deg split point #25 drill such as McMaster-Carr PN: 28765A75 spot drill the barrel through the open set screw hole. A hand drill works well for this step. All that is needed is a dimple so that the set screw enters into the dimple and does not pull up proud bumps when tightened. It also puts the setscrew in shear from any axial or radial loads applied to the gas block in service. Blow out chips from drilling and install and tighten the 2nd set screw. Now remove the 1st set screw and dimple the barrel through that hole. Re-install the 1st setscrew. Re-check gas tube alignment. It is permissible to use a locking compound such as Loctite Blue on the set screws.

https://d3cfki0l5o2ps6.cloudfront.ne...s-block-ai.pdf

I do like the SLR jig, though.

[elephantrider]

I have the BRDE jig. For those hand drilling the dimple, what are you doing to support the barrel? Also, I'm looking for some advice on drill press or small mill that can do this job and others. I have some other uses for such a tool.

NC

Using dimple jigs and a hand drill, I have just held the barrel/jig by hand, or lay it on a table/floor while drilling. I didn't find that the jig was too difficult to hold, or that the jig would would move. Pretty easy really. If you have a drill press with a vise set up, that is a no-brainer also.

If I was dimpling w/o a jig, I would use a drill press or mill and start with a spotting drill to get the dimple located and started. Once the spotting drill has created a hole large enough that the regular drill bit wont slip off, you can finish it off with a regular bit.

[ScottsBad]

If you have a jig and a drill press, just go down to Harbor Freight and buy a cheap drill press vise. They're only a few bucks and you'll use it over and over. Barrels are fricken hard, so don't worry about easily drilling through. Use a little Tap Magic or really any synthetic oil. Put a few drops in the jig hole. Drill carefully for a couple seconds. Clean out the hole and look in with a flashlight. I've only done a couple, but I like to make a dimple as wide as the bit, but not deep. That way the screw can fully engage the dimple. Drill and look as many times as necessary until the dimple is to your satisfaction. I think it would be hard to use the depth stop on a drill press unless you are doing a lot of barrels.

Clean the gas block and screw with carb cleaner to remove all oil. Install with high temp Loctite red. Let sit for 24 hours.