AR15.Com Archives
 Replacing broken carrier key bolt... any secrets ?
StealthyBlagga  [Member]
6/26/2010 6:23:41 PM
One of my carrier key bolts broke. I have replacement bolts in hand (I am going to replace both bolts just to be safe). Is there any special procedure for doing this (e.g. clean the threads with unobtanium, whatever) ? Should I use Loctite or just screw them in tight, restake and trust the staking to hold it in place ?
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hotdog250j  [Team Member]
6/26/2010 6:29:19 PM
the allknowing "they" say overtorquing those little screws is bad, m'kay?
Gregory_K  [Team Member]
6/26/2010 6:38:20 PM
just go with the tm.
StealthyBlagga  [Member]
6/26/2010 6:58:32 PM
OK, there is almost nothing to grab hold of . Any secrets for getting the broken piece out ?
Gregory_K  [Team Member]
6/26/2010 7:32:27 PM
small screwdriver or a small punch and tap it in the direction to unscrew the thread.
Gatorhunt  [Team Member]
6/26/2010 7:59:48 PM
Easy out set
StealthyBlagga  [Member]
6/26/2010 8:23:01 PM
OK, I got it out. I drilled the center of the screw with a 7/64" bit, then used small needle files to slowly widen the hole until all that was left was the residue in the threads, which I picked out with the tip of the needle file using a magnifying glass to see what I was doing. Oh yeah, and out came a whole bunch of red Loctite that the previous owner must have thought was a good idea . What a huge PITA.

I have chased out the threads with a 8-32 tap, so I am ready to install the new bolts. Just to be clear, I install them snug but not over-tight, and I don't use any threadlocker - right ?
Tyrone  [Member]
6/26/2010 8:43:08 PM
Originally Posted By StealthyBlagga:
OK, I got it out. I drilled the center of the screw with a 7/64" bit, then used small needle files to slowly widen the hole until all that was left was the residue in the threads, which I picked out with the tip of the needle file using a magnifying glass to see what I was doing. Oh yeah, and out came a whole bunch of red Loctite that the previous owner must have thought was a good idea . What a huge PITA.

I have chased out the threads with a 8-32 tap, so I am ready to install the new bolts. Just to be clear, I install them snug but not over-tight, and I don't use any threadlocker - right ?


According to the sticky, you want 35-40 INCH pounds which is ~3 FT/LBS. I use one of those bendy torque wrenches for the carrier key bolts as you can better control the amount of pressure you are applying.
bloodsport2885  [Team Member]
6/26/2010 8:44:43 PM

Originally Posted By StealthyBlagga:
OK, I got it out. I drilled the center of the screw with a 7/64" bit, then used small needle files to slowly widen the hole until all that was left was the residue in the threads, which I picked out with the tip of the needle file using a magnifying glass to see what I was doing. Oh yeah, and out came a whole bunch of red Loctite that the previous owner must have thought was a good idea . What a huge PITA.

I have chased out the threads with a 8-32 tap, so I am ready to install the new bolts. Just to be clear, I install them snug but not over-tight, and I don't use any threadlocker - right ?

The toque values for those screws are in inch lbs so hand tight should do it. Threadlocker is pretty useless due to how hot the BCG gets during firing but it won't hurt anything if that is what you mean. A good stake job is all that is needed to keep the screws from backing out.
Engineer5  [Team Member]
6/26/2010 9:23:39 PM
Here's from a page at Young Manufacturing



Staking the gas key on the AR-15 and M-16 carrier.

There has been a lot of talk about the pros and cons of staking the gas key on the carrier. Here is our opinion and why Young Manufacturing will not stake keys. We have been making carriers since 1991. The US Mil Spec. assembly drawing requires the carrier key to be staked. Contrary to some popular opinions staking does not “SEAL” the gas key. Staking keeps the screws from backing out Period. If you do not properly torque the screws to 56 inch pounds you will be staking a screw that is loose or one that is over torqued and prone to breakage. We have seen plenty of staked screws that are loose or broken. The Mil Spec. also calls for the gas key bottom surface to be “SEALED” with Permatex gasket sealer. Something no one does to our knowledge. Here is our procedure for installing a gas key. First clean the oil from the gas key and the mating surface on the carrier. Then clean the oil from the screw threads. We use break cleaner for this. Next use a very light coating of Permatex high strength thread locker gel on the bottom of the key. PN 27010. This is much easier to use than the Permatex gasket sealer. It comes in a plastic twist dispenser. Make sure you don’t use so much that it squishes into the gas port hole. The cure rate is 60 minutes. Next coat the screw threads with the same gel. Install the key and torque the screws to 56 inch pounds. Should you decide to remove the key for some reason don’t use the old screws when you put the key back on! You will most likely break them during installation or when you fire the rifle. Go to the local hardware store and buy new 10-32 x ¼” SHCS. If you feel the need to stake the screws spend the money and get one of the staking tools from Brownell that uses a screw type system to swedge the material into the top of the screw. Don’t use a hammer and a punch! You can stretch the thread on the screw and now you have a loose screw that will eventually break if the gun even fires. We will not warrantee a carrier with a staked key no matter who staked it. You will be charged for a new key and any labor required to remove broken screws.

Good Shooting!

Daniel H Young
President
RLR350  [Team Member]
6/26/2010 11:58:37 PM
Here is Armalite's Technical Note that also suggests a torque of 55 inch lbs. vs. the 35 - 40 inch lb. recommendation in the manual. Very similar to Young's recommendation posted by Engineer5.

ETA: The Wheeler Fat Wrench works great for gun related inch pound torque.
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