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Posted: 6/29/2016 10:16:50 AM EDT
The gas key on my AIM LW carrier came loose after about 500 rounds of simulated full auto from my binary trigger. Bryan at AIM offered to replace the BCG, but I didn't want to pay the shipping back to AIM or wait for a replacement. Here is the process I followed for fixing the key. As you can see, the staking is heavy enough that the front screw won't come out of the carrier key, but it spins underneath the staking.  I acquired new Torx Plus gas key screws that exceed the grade 8 standard. These are McMaster Carr Item number 92610A190 http://www.mcmaster.com/#92610a190/=10yg49o  Then I cleaned the carrier. Took awhile. After cleaning I degreased the mounting surfaces and screws with brake cleaner.  After degreasing I applied Permatex No3 sealant. This application was a little heavy, but it shouldn't cause any issues.  I then applied Permatex High Temp thread locker to the gas key screws and gave the Permatex No3 a few minutes to set up. Then I seated the gas key, torqued the screws to 56 in/lb and re-staked the screws with a large flat bladed screw driver and a ball peen hammer. A light tap and it pushed the metal into the screw. You don't want a thin blade, as the goal is to push the metal and not cut it. I also start light on the hammer strikes. You can always hit it again. Now she's ready to go back to work.  I originally posted these pictures in another thread and it was suggested I put together a quick how to that people could search and find. Hopefully some people will find it helpful. |
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Posted: 6/29/2016 10:23:52 AM EDT
[#1]
Very nice. I had a similar issue about a year ago with my bushmaster gas key coming a little loose. I did a similar but less thorough fix
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Posted: 6/29/2016 11:19:21 AM EDT
[#2]
Mods,this needs to be a sticky...
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Posted: 6/29/2016 12:54:26 PM EDT
[#3]
Quote HistoryQuoted: Mods,this needs to be a sticky... |
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Posted: 6/29/2016 1:03:34 PM EDT
[#4]
Great write up. I'll keep this in mind should I ever encounter the same problem.
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Posted: 6/29/2016 1:34:46 PM EDT
[#5]
Well done
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Posted: 6/29/2016 3:05:17 PM EDT
[#6]
Good post!
I've been using ASTM A574 Torx Plus screws for the carrier key screws for years. |
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Posted: 6/30/2016 2:11:59 PM EDT
[#7]
Quote HistoryQuoted: I concur. Quote HistoryQuoted: Quoted: Mods,this needs to be a sticky... |
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Posted: 7/1/2016 12:09:38 PM EDT
[#8]
Tagging for reference. Thanks for taking the time to document.
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Posted: 7/1/2016 6:09:22 PM EDT
[#9]
Thank you for taking the time to post up the pictures. That's one hec of a good job.
Tagged for sure |
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Posted: 7/2/2016 6:46:42 AM EDT
[#10]
Not to ask a stupid question, but how did you hold the bolt carrier while you were staking it?
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Posted: 7/2/2016 9:18:26 AM EDT
[#11]
Quote HistoryQuoted: Not to ask a stupid question, but how did you hold the bolt carrier while you were staking it? |
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Posted: 7/2/2016 10:06:25 AM EDT
[#12]
Thanks, j. During the last general panic and shortage of AR parts, I had to buy a bare carrier from one supplier and a key w/screws from another. I prepared the surfaces and coated the flats with the same permanent threadlocker used on the screws. I staked the heads with a small cold chisel. I like your idea of using a flat-tip screwdriver for the staking, I may try that if I ever have to install a gas key again. - CW
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Posted: 7/2/2016 3:39:15 PM EDT
[#13]
Nice to see somebody that doesn't go crazy with the staking.
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Posted: 7/9/2016 11:38:21 AM EDT
[#14]
I just did the same fix today with permatex red gasket maker around the gas port hole. I used a Moacks to stake the key. The front screw on the gas key was broken so I had to extract the front screw fragment. I think some venders use cheap screws. I used a BCM gas key kit to replace the original key and screws. I still need to test fire it.
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Posted: 7/27/2016 11:31:17 AM EDT
[#15]
Quote HistoryQuoted: I just did the same fix today with permatex red gasket maker around the gas port hole. I used a Moacks to stake the key. The front screw on the gas key was broken so I had to extract the front screw fragment. I think some venders use cheap screws. I used a BCM gas key kit to replace the original key and screws. I still need to test fire it. |
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Posted: 7/27/2016 12:28:08 PM EDT
[#16]
Quote HistoryQuoted:
I just did the same fix today with permatex red gasket maker around the gas port hole. I used a Moacks to stake the key. The front screw on the gas key was broken so I had to extract the front screw fragment. I think some venders use cheap screws. I used a BCM gas key kit to replace the original key and screws. I still need to test fire it. Keep in mind, I'm concerned when I see an advertisement listing Grade 8 carrier key screws. The Grade 8 standard for Socket Head Cap Screws "went away" several decades ago (in the U.S.) and was replaced by the ASTM A574 standard. (STRONGER than Grade 8) ASTM A574 Socket Head Cap Screw • Tensile Strength: 180,000 PSI minimum (through 1/2”), 170,000 PSI minimum (above 1/2”) • Proof Strength: 140,000 PSI (through 1/2”), 135,000 PSI (above 1/2”) • Yield Strength: 153,000 PSI minimum • Hardness: HRC 39-45 (through 1/2”), HRC 37-45 (above 1/2”) The initial heat-treating process is relatively the same for all three products. The parts are heat treated until fully austenitized. The parts are then quenched and tempered in a liquid (oil). This final tempering temperature is what will dictate the final product. There are "offshore" Socket Head Cap Screws being sold and advertised as "Grade 8". |
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Posted: 7/28/2016 12:39:44 PM EDT
[#17]
Why aren't grade 8 bolts good enough?
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Posted: 7/28/2016 12:43:11 PM EDT
[#18]
Quote HistoryQuoted: Why aren't grade 8 bolts good enough? |
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Posted: 8/6/2016 7:46:22 AM EDT
[#19]
Quote HistoryQuoted:
Who manufactured the bcg? Quote HistoryQuoted:
Quoted:
I just did the same fix today with permatex red gasket maker around the gas port hole. I used a Moacks to stake the key. The front screw on the gas key was broken so I had to extract the front screw fragment. I think some venders use cheap screws. I used a BCM gas key kit to replace the original key and screws. I still need to test fire it. Spikes, now it works like a champ. Super easy fix with the right tools. I used a FAT torque wrench and the pocket moacks. |
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Posted: 9/7/2016 3:26:04 PM EDT
[#20]
I need to find the TM and make sure I'm listing the correct torque. Dano listed 37in/lb in a recent thread. ETA: Found one of the old TM's that list's 35-40in/lb. Also found this thread that says the new manual states 50-58in/lb and Armalight specs 55in/lb. http://www.ar15.com/forums/t_3_4/590110_Gas_Key_Screw_Torque_.html I'm happy with my earlier 56in/lb, I think anything in the mid 50's is good. |
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