Sheared off gas key

[Stape]

The gas key on my bolt Cartier shear off. Well, the screws that hold in on anyway. The screws are broken off flush with the top of the carrier. I have been using a drill press and a 5/64th easy out bit to get the remains out of the carrier.

Is there some trick to drilling these pilots? I've been going at it for a good bit with brand new 5/64 drill bit and making minimal headway. Can't really put anything behind it cause those bits are so small and will flex/break.

Any pointers or is it just a slow tedious process? I imagine the key screws are hardened or something.

 

[Chet0729]

If you can get a small milling bit they work better. Like the ones that come with Dremels. Those screws are most likely hardened and will require a good steel bit to drill. The small carbide milling bit would be a better option.
have yo tried walking the screws out with a small chisel and hammer. A lot of times you can turn them out using this method.

 

[Stape]

Haven't tried walking them out. I don't have a chisel that small. I might take an old extra punch and grind it down to make one though. Right now my efforts have yielded just small dimples in the screws.

 

[Wildweasel]

regular high speed steel (hss) is not going to cut it. you want a cobalt or carbide bit. Use a slow speed and coolant of some sort (oil)

Or just walk it out if possible.

 

[pastera]

I have some carbide endmills and drills in 1/8"
You will need a good set up in order to not shatter them though.

 

[warwickben]

Harden bolts, that probably have lock tight mixed in .

Need a vise firmly mounted to a mill or drill press.

If there's any angle to where it broke you'll need to get a flat put on there. A ti coated end mill should help you do that ,
If a good center drill wants to walk.

Center drill= high speed and just peck. So you make a small divit.

Or

Take a center punch and put a nice clean dent in the .

Put drill press/mill on slow 150-200 max

Once it starts cut just keep equal pressure on the drill and plenty of oil.

Frog lube works great for cutting oil. Since I stopped using it as lube , I just been using the rest of it to drill rivets and screws out .

 

[mac1911]

If there is loctite try heating with a soldering iron.
What manufacture on the BCG?
I often have great luck useing a little heat right on the broken bolt hit it with a dab of bees wax. The bees wax wicks in like solder. I also use left handed bits. 80% of the time the bit will grab and walk the bolt out... good luck go slow.

 

[Chevy 2 65]

Why not just buy a new one?

 

[ScottS]

Milspec bolt carriers are cheap and plentiful these days. With a complete bolt carrier group selling for $69 (8620 chrome-lined carrier, C-158 bolt) at PSA, how much work do you want to do to drill out hardened screws?

 

[mac1911]

Why not just buy a new one?

heck maybe to work on a little repair skills ?

 

[ScottS]

heck maybe to work on a little repair skills ?

If drilling out hardened screws is one's idea of fun, sure. But it's not exactly a "day-to-day" repair on an AR.

 

[warwickben]

I'd trade a national match carrier for you broken bcg ....

I'm going to cut it in half any ways for my bullpup build .

 

[mac1911]

If drilling out hardened screws is one's idea of fun, sure. But it's not exactly a "day-to-day" repair on an AR.

not so much for fun but any time to build your skills in fixing stuff yourself is good. Drilling hardened screws is not hard with the right bits/tools.
Im sure broken screws happens more often than you might actually see. most AR shooters are not putting enough ammo down range to even put wear on their ARs.
Im going to gander that if you ask a marine/army armorer about broken gas key screws he sees it alot. I doubt they chuck the entire BCG because of it.
Ok pressed for time dont want to buy tools thats fine buy a new one.

- - - Updated - - -

I'd trade a national match carrier for you broken bcg ....

I'm going to cut it in half any ways for my bullpup build .

now I would take you up on that offer, good part for a broken part......nice. I dont have a broken BCG.

 

[Chevy 2 65]

heck maybe to work on a little repair skills ?

yeah, thats it

 

[Fixxah]

Got ICE? J/K.

Nothing is more satisfying than fixing stuff for yourself.
I like the left twist drill and beeswax ideas.

 

[DrBurnsides]

Left handed Carbide steel bits. Best money I ever spent..

 

[mac1911]

Got ICE? J/K.

Nothing is more satisfying than fixing stuff for yourself.
I like the left twist drill and beeswax ideas.

When i started in the auto repair business one of my first jobs was at a exhaust shop. Guy I worked for was the go to guy in the area for broken studs and manifold bolts.
I was amazed at how well the bees wax trick worked on helping old rotted broken studs come out and the left hand drill bit trick. He also did all the broken plow bolts repairs in the area.

I have some really long bits that are great for hard metal from this place. http://www.wlfuller.com/html/drills_for_hardened_steel.html

 

[Stape]

Thanks for all the help fellas. I'm down at Camp Lejeune right now and have been traveling since I originally posted.

why not but a new one? I like to fix stuff whenever I can, build experience and learn. Ben, I'd happily trade you. Thanks for the offer, let me know. This rifle sees about 500 rounds every outing, up to a couple times a week. No idea on the manufacturer of the bolt. The only markings are the letter E stamped on the carrier and the bolt. Hope I hit all responses. Thanks again. I'm going to look into some left hand carbide bits. I have a nice drill press and vise.