AR-15 bolt carrier key

[DesertMarine]

Bolt carrier key screws on my two Oly uppers are staked.

[tombogan03884]

I read the same article and wondered something I will ask here. What are you talking about ? In my experience as a Marine and NG unit armorer the "Bolt carrier key" is the T shaped pin that locks the bolt into the carrier body, it cams the bolt out and is held in place by a STRAIGHT cotter pin as it must be removed to dis assemble the bolt and carrier for cleaning.

[Big Frank]

I read the same article and wondered something I will ask here. What are you talking about ? In my experience as a Marine and NG unit armorer the "Bolt carrier key" is the T shaped pin that locks the bolt into the carrier body, it cams the bolt out and is held in place by a STRAIGHT cotter pin as it must be removed to dis assemble the bolt and carrier for cleaning.

Tom, that's the bolt cam pin.

The bolt carrier key is the part on top of the carrier that fits around the gas tube and funnels the gas into the carrier.

[tombogan03884]

OK, Makes sense now 

[Big Frank]

Well, like my friend just said after sending me an email but forgetting attach the picture... Oooopsie!

[Sponsor]

[tombogan03884]

[JohnZ]

It's not that the keys are merely staked, but that they're PROPERLY staked to mil-specs. The staking on a Bushmater is generally more superficial than, say, a Colt 6920. If they're not staked properly, they'll probably come loose at the worst time.

[Big Frank]

The screws are only torqued down to 35 to 40 inch-pounds so staking is mandatory. I wish I could post pictures from my manual. I have a PDF version too but don't know how to save pictures from it. You need to use a center punch and stake around the edge of each screw 3 times. If you replace the key you're supposed to use new screws too.

I know a quick and dirty way that also works if you don't have a center punch, but it's not mil-spec. Just use a dull cold chisel and stake each screw going down at a 45 degree angle on the edges of the key. It's not pretty but as long as you don't raise the metal over .025" above the top it works. That's a field expedient method for emergencies that's not in any manual.

[JohnZ]

The screws are only torqued down to 35 to 40 inch-pounds so staking is mandatory. I wish I could post pictures from my manual. I have a PDF version too but don't know how to save pictures from it. You need to use a center punch and stake around the edge of each screw 3 times. If you replace the key you're supposed to use new screws too.

I know a quick and dirty way that also works if you don't have a center punch, but it's not mil-spec. Just use a dull cold chisel and stake each screw going down at a 45 degree angle on the edges of the key. It's not pretty but as long as you don't raise the metal over .025" above the top it works. That's a field expedient method for emergencies that's not in any manual.

One of my carriers came correct from the factory. The other one I just did with a hammer punch in a vise, looks OK but I haven't fired many rounds with it so I don't trust it yet. Chances are it'll be adequate.

I'm not positive, but I think C4IGrant on M4carbine.net said 60 -in pounds is what the screws are supposed to be at. Is posting links to other carbine forums OK here?

Sorta OT, but for the record, I don't think staking is rocket science; it just makes me wonder that if a manufacturer has poor enough QC to let crappy staking roll off their lines, then what else will slip through? 

[Big Frank]

I got my information out of ARMY TM 9-1005-319-23&P and AIR FORCE TO 11 W3-5-5-42, which is all one manual and was up to date as of 1997. I haven't seen a newer version of this manual but it could possibly be out-dated. MARINE CORPS TM 05538C-23&P2 from 1984 says the same exact thing, 35-40 inch pounds, and the 1991 Army and Air Force manual, updated in 1997, is supposedly based on it. As I used to say when I was in the army... hey, it's good enough for government work.    I wouldn't torque it any tighter and risk stripping the threads unless I see a manual that reccomends higher torque.