Question about gas key

Check for Gas Key obstructions with a .080 or smaller diameter weed eater line. Things like Blown Primers can find their way in there.

DO NOT use q-tips, pipe cleaners, or sharp objects. They can break and get lodged in the Gas Key. The weed eater line is NOT for cleaning, it’s simply to check for obstructions ONLY. If there is an obstruction its best to replace the Gas Key and Gas Key Bolts. When doing this operation ensures the Gas Port in the Bolt Carrier is free of obstructions.

Inspect Gas Key Bolts for breakage and proper staking.

To check for breakage, insert a 1/8” or 9/64” Allen Tool/Wrench (There are 2 size heads used) into the Gas Key Bolts and use a reversible Torque Wrench set at 30 INCH POUNDS (This is the LOWEST SETTING, I prefer them to hold @ 50 Inch Pounds but we will use 30 Inch Pounds as the lowest #), if it breaks lose then replace the Bolts. This should tell you if the Gas Key Bolts are broken or are not torqued and staked properly. It will sometimes take 90-100 Inch Pounds or more to break loose Gas Key Bolts. If ANY Gas Key Bolts break loose, remove BOTH Gas Key Bolts and replace them with NEW (Grade 8) 8-32 x ¼” Long Bolts (DON’T BUY THEM FROM THE HARDWARE STORE). Broken Gas Key Bolts will result in short stroking malfunctions.

Proper staking is a visual inspection. The Gas Key metal should be displaced well into the Gas Key Bolts. Staking is not just to keep the Gas Key Bolts from loosening from recoil and heat expansion, but also helps retain the Bolt Heads if the event of a head separation. If they are not staked they can dislodge when they break, which cause the Bolt Carrier Assembly to lock up, and in VERY rare cases find their way into the Fire Control Assembly in the Lower Receiver, causing a failure to fire.

If there is insufficient metal displacement then use a Gas Key Staking Tool (MOACKS from M-Guns) to correct the problem. You can also use a spring loaded center punch and stake from the TOP (Field Staking). DO NOT use a hammer and chisel/punch to stake the Gas Key on the top or sides. Using a Hammer can stress or break the Gas Key Bolts. I suggest owners use a straight edge and scribe a line across the top of the Gas Key and the Bolts, this works as an indicator that the bolts have rotated when doing P.M. or Cleaning.

Inspect Gas Key for proper mouth flaring and straightness and looseness with a #14 or #15 Drill Bit. If neither bits fit the Gas Key is crushed or burred internally. If the Gas Key is not flared, use a Re-Flaring Tool Set. If you don’t have a Re-Flaring Tool Set, replace the Gas Key and use NEW Gas Key Bolts. A lack of mouth flaring will lead to rapid Gas Tube Flange wear and will result in short stroking. Using#14 or #15 Drill Bit, inserted into the Gas Key, visually check the Gas Key for straightness, drooping, and lift. If there is any alignment issues REPLACE the Gas Key.

When reinstalling or replacing the Gas Key you should use a flat stone to “plane” or “deck” the surface. This creates a better mating surface and also ensures there is no old material that shouldn’t be there. Green Loctite 620 or Permatex gasket sealer should then be applied to the DEGREASED and stoned surface. Do NOT get any gasket sealer or Loctite into the Gas Key or Bolt Carrier Gas Ports. These measures are to ensure that there are no leaks when parts expand under heat. Leaks in this area will lead to more fouling to get into the Upper and Lower Receiver, and will lead to cycling issues. Ensure that the Gas Key Bolts are NEW Grade 8 10-32 x ¼” Fasteners (DON’T BUY THEM FROM THE HARDWARE STORE). Clean the Bolts well and lightly lubricate them and install them with 50-58 Inch Pounds of Torque and let it set overnight before additional lubing or firing. Some Military Manuals and Manufacturer’s Instructions call for 35-40, 49-52, and some 50-58) DO NOT exceed 60 Inch Pounds and DO NOT use any thread locker, gasket sealer, or Rocket for the Gas Key Bolts. Some manufacturers tell Armorers to go to 55-56 Inch Pounds, Loctite, Rocksett, or Permatex the Gas Key Bolts, and to avoid staking. Excessive torque ratings can stress the Gas Key Bolts to the point of breakage when they heat up and expand. Loctite and Permatex is a superb gasket product for this high heat application, but perform poorly for threads when exposed to high heat applications. Loctite breaks down at 300 degrees and a Gas Key can reach that operating temperature with sustained fire. Rocksett is superb for this application but can make removing the Gas Key Bolts difficult. Soaking the Bolt Carrier in water will release the Rocksett if you choose to use it. Thread Lockers will also make removing a broken Bolt from the Bolt Carrier more difficult and require heating the part.

Inspect the Gas Key for raised staking burrs.
This is performed by running the Gas Key inside the Charging Handle Stem. If there is any binding, use layout fluid or a sharpie on the staking marks and redo the test. This will locate the source of the friction. Use a file or stone to smooth out the burr.

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Sticky said:

Thanks for sharin that tidbit of knowledge Chad!

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