When I was cleaning my AR, I dropped the bolt carrier on the gas key bending it. I couldn’t get it straight enough to work, and Bravo Company was out of stock, so I headed down to the local gun show and picked up a key and screws.
Looking at it, it looked like it was good quality. It was chromed inside and parked on the outside. I took it home and installed it according to the directions in the Marine Corps manual and went shooting. The first time out the gun ran fine but I didn’t have time to fire many rounds. The next time out it ran fine for a few magazines but after that it failed to cycle every five our so rounds.
I brought it home and compared the key installed to the one on an LMT carrier. At first I didn’t notice anything different, then I inverted a can of compressed air and blew it through both keys. On the LMT carrier, most of the air blew out through the carrier. On my carrier most of the air blew back out through the key. Looking inside both keys with a flashlight, I discovered the key I had boght was missing the shoulder inside that the LMT carrier had.
I stopped by Rainier Arms and picked up a carrier key take-off and installed it. The next time out I ran over 400 rounds through the carbine with no failures of any kind and all the rounds dropping into the 5 o’clock area.
Moral of the story? Don’t take any chances. Buy quality parts from reputable companies.
If you look inside the gas key, there is a shoulder at the back. My assumption is the gas tube sits against this shoulder when the carrier is forward. The defective gas key didn’t have that shoulder.
Mmmm…don’t see a shoulder in my keys. Oh well, at least you got the problem corrected.
Did you by chance match up the position of the gas port on the bottom of the two gas keys? I wonder if the defective gas keys gas port did not mate up exactly with the bolt carriers gas port.
I compared the old and new side by side visually and couldn’t see a difference. That’s not to say there wasn’t, but that’s the point of the post. Most end users don’t have the knowledge or capability to tell if a specific part was made in spec, with right materials, etc. Most guys selling parts at gun shows don’t either. That’s why I think it’s so important to buy your parts from reliable vendors.
It is also important that the bottom of the gas key be stoned flat before it is installed to ensure optimum reliability. Did you stone it before assembly?
No, I didn’t stone it. Both times I did the replacement using the instructions in the Marine Corps TM. It does mention that, when repalcing the key, three to eight rounds may need to be fired to form a seal between the key and the carrier.
I will never ever trust anything that is not a reputable brand. I got burned 3 times with “cheaper” gun show parts. It’s not cheaper when you have to buy it twice.
The other moral of the story: put something soft on the floor of your workspace.
My neighbors make fun of me for having put (old) carpet my garage around my workbenches, but when I inevitably drop stuff, it doesn’t break, it doesn’t bounce away, and it doesn’t roll away. It’s just laying there for me to pick it up again. And when I put delicate stuff on the floor, I don’t worry about scuffing it, either.
+1 The motto I live by is “only a rich man can afford to buy it twice”.
There is so much counterfeit garbage out there that you really cannot afford to buy from anyone other than a reputable business (like G&R Tactical, Bravo Company USA, Larue Tactical, Brownell’s, DSG Arms, et. al. I have made multiple purchases from each of these vendors with 100% satisfaction.)
Coming from a civilian’s standpoint, I think there’s a gray area.
I have purchased some accessories which were ‘budget’ or cheaper.
My VFG cost me $12. But if that broke, my firearm is still usable. I have a budget optic ¶ but again, if that broke, I flip a switch and I’m back to irons.
On the other hand, I bought a used firearm of unknown brand (ADCO tells me it’s an Oly). I’m glad I didn’t have to defend myself with it when I first purchased it. Somehow the extractor was bent - with only the spring, it wouldn’t extract reliably, but with the insert, the bolt would get stuck back causing a short cycle. I’ve recently purchased a BCM BCG.
