AR15 Gas Key Screw Torque Specifications.

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AR15 Gas Key Screw Torque Specifications.

Postby Texas Sheepdawg » Wed Apr 18, 2012 5:31 pm

Here is a cut & paste from another forum:
QUOTE.
For years, veteran ArmaLite® assemblers have tightened carrier keys using a simple Allen wrench. This process has been successful.

As we added employees we decided to use calibrated torque wrenches to assure that we secure the key screws to the proper level. The government standard for carrier key torque is 35 to 40 inch pounds, and we secured torque wrenches set to that value. We then noticed an INCREASE in loose carrier keys. It turns out that we had tightened carrier key screws better without the wrench than with it. 

The problem is that the government torque values shown in maintenance manuals are too low.

We have examined the engineering data related to the screw itself, and have increased torque to 55 inch pounds to improve carrier key tightness. We recommend that all AR owners make sure that their carrier key screws are secured to this level, especially if their rifles sometimes shows signs of weak or slow cycling.

If your AR “short strokes,” clean the underside of the carrier key and tighten both screws to 55 to 60 inch pounds. Tighten the front screw first. If your rifle isn’t short stroking, just make sure that the screws are tight and restake if needed.
UNQUOTE
Also found this.
Quote
Civilian 35-48 inch pounds
Mil Spec 50-58 inch pounds
UnQuote
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Re: AR15 Gas Key Screw Torque Specifications.

Postby tridentarmory » Sun Apr 13, 2014 7:37 pm

we tighten to a straight 60, and at that point they feel like there isnt much left in them.
staking is critical, and we have found that more is better with key stakes
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Re: AR15 Gas Key Screw Torque Specifications.

Postby Texas Sheepdawg » Mon Apr 14, 2014 10:25 am

I couldn't agree more about staking. The gas key and the little screws that hold it should be totally replaced if ever removed, with NEW gas key and a pair of NEW gas key screws. It only costs $20 or so to do this. The consequences of not doing so could be catastrophic.
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Re: AR15 Gas Key Screw Torque Specifications.

Postby MarkCO » Mon Apr 14, 2014 8:23 pm

Staking a gas key screw that had been stretched too much (due to high torque levels) is known to sheer the screw at the thread root. The original design called for a sealant (hi temp aviation grade) and higher torque level. There are a few companies that build the carriers correct (sealant, higher torque values, and no staking) and they do not get failures nor leakage.

A little less torque and the staking is required because the threaded fastener has not differentially stretched which does in fact create a lock. Just think about all those cylinder heads out there with sealant, no thread locker and no staking. Threaded fastener technology has been well established for years, but most in the firearms industry are not up to date on it, for a variety of reasons, but that does not make the technology wrong. :o
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Re: AR15 Gas Key Screw Torque Specifications.

Postby MarkCO » Thu Jul 10, 2014 9:16 am

Had another gas key failure brought in today. Heavy staking...bolt sheared right at the thread root. The release torque on the rear bolt was 51 inch-pounds which would have put it at about 55 tightening torque. Honed the face of the carrier, new gas key, new fasteners, Permatex Aviation #3 sealant and 60 inch-pound torque.
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