Took my carbine to the range this weekend. Everything seemed to be functioning fine up until I was getting ready to pack it in. On my last magazine the BCG didn’t seam to be cycling fully to strip the next round. I would cycle the action, chamber a round and end up with a single shot. I inspected the rounds in the mag, Lake City 55gr, M193; no issues there that I could see so I packed up the rifle until I could get home and give it a proper look-see.
Upon disassembly I could see that the carrier key was visibly and physically loose, even with what appeared to be adequate staking. It appears to me that I was bleeding way too much gas, causing the cycling issue.
Here is my question, should I remove and re-torque the existing key and re-stake or should I replace the key and screws and then re-torque and re-stake. What say you guys?
Get a new key and new screws at a minimum. Remove the old key and inspect your bolt carrier to make sure it’s still OK. If the mating surface or threads on the carrier are screwed up, replace that too.
Who makes the BCG? I would remove the key, clean the area real good and possibly use some very fine sand paper. If everything is good then torque the screws and restake correctly.
New key and screws have been ordered. I am also ordering a new carrier assembly from BCM and will relegate this one to “spare” status; it never hurts to have a back-up. For now it has been cleaned, reassembled, and re-staked per IG’s instructions as I am now curious to see how many rounds it will go and if it will work loose again.
I bought this one before I found this site and became “educated”. The company who made it, Anvil Arms, is no longer in business so no recourse there. As I intended this build to be educational it is clearly serving that purpose. Thanks for the responses.
Thanks for sharing. A classic example of what we talk about here every day. Stake that key down GOOD. In this case you say it appeared to have been well staked. Not sure if you are still able to show this original staking job, but if you can share a pic?
I know BCM gas keys are staked very well as are the castle nuts. Looks like a Gorilla did the staking. You’d need a 6’ cheater bar to get those screws out!
On carrier keys to ensure that they are sealing correctly here’s how I do it:
Remove carrier key.
Discard old screws.
Degrease carrier and key.
Lap the bottom of the key on a course stone I have. This removes the finish from the bottom of the key and makes sure that the key is perfectly flat.
Clean off the key.
Apply a little Rocksett to the bottom of the key and set it on the cleaned off carrier.
Install new carrier key screws hand tight.
Torque each to 50-55in lbs (I torque the front one first).
Stake with a MOACKS, you don’t have to use a MOACKs but it makes the job very easy and very fast.
If the staking caused large burrs to stick up above the key I dress then down a little with a stone/file.
I’ve never had a single one come lose nor leak using this method.
i cleaned the Y/M bolt carrier with brake cleaner -no damage to flat area ,where the gas key fits .got a new gas key from Y/M ,it came with two bolts and high temp red loctite . with info on how to-tighten to 35 inch pounds -red loclite put lightly on under side of the key as well on the threads …well today i shot the weapon yes i have been working too long on other thing —flawless working now …