The Down Range Forum
Member Section => Tactical Rifle & Carbine => Topic started by: Big Frank on December 21, 2008, 03:56:33 PM
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I read a review today about the Charles Daly M4 style AR-15. They made a big deal about how the the bolt carrier key screws are staked in so they don't come loose. I thought all AR-15s had the carrier key screws staked at the factory, just like all real M4s and M16s do. I never saw any that weren't. I just checked both of my EBRs to confirm each screw is staked in two places. I was wondering if some of you guys can check yours and tell me if they're staked or not. If yours aren't staked I can show you the field expedient method that the army and marines use, plus an alternate method.
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Sounds like a 'fiddlely part ' issue. I'll check mine when I'm in 'fiddlely part' fiddle. I've got to find a good exploded view of the AR15 - DPMS book is kinda sketchy on the illustrations.
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When they said the screws were staked in... well, it seemed like saying the trigger is held in by a pin, or something equally obvious.
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A lot* of reviews of anything are mostly written by press releases and just edited by the writer. Have you ever listened to plumbing ads or reviews that talk about how little water their fixture use only to realize they are just following National codes on water usage, or car reviews talking about all the features of a car like power windows and locks, a/c, cruise, etc and then tried to find a car without those things?
Manufacturers will list everything on their product to make it look impressive, even if everyone has it.
* Note that I said "a lot" not "all."
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That's true. But I expect gun magazines and their writers to know more about a 50 year old design that they've reviewed over and over again. I almost said respected gun magazines. ;) Next they'll be telling us about a new M1911A1 that has some kind of new-fangled feature like a grip safety. ::)
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That's true. But I expect gun magazines and their writers to know more about a 50 year old design that they've reviewed over and over again. I almost said respected gun magazines. ;) Next they'll be telling us about a new M1911A1 that has some kind of new-fangled feature like a grip safety. ::)
Haven't you ever noticed the raves on the innovative grip safety on a polymer gun like it had just been invented, or the wonderful ergonomics of the beaver tail on brand x's newly released 1911? I don't see it in every gun review I read, but the common is re-hyped quite often. Just last month I read of a new rifle with a "new innovative three position safety." Ahhhhhhhhhhhhhh ... how long ago was this article written?
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Hey...they didn't even mention the chrome plated muffler bearing...
Michael B
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Or the the low energy used in the improved flux capacitor ;D
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Dambit! DPMS manual doesn't have either of those parts in the schematic!
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I read a review today about the Charles Daly M4 style AR-15. They made a big deal about how the the bolt carrier key screws are staked in so they don't come loose. I thought all AR-15s had the carrier key screws staked at the factory, just like all real M4s and M16s do. I never saw any that weren't. I just checked both of my EBRs to confirm each screw is staked in two places. I was wondering if some of you guys can check yours and tell me if they're staked or not. If yours aren't staked I can show you the field expedient method that the army and marines use, plus an alternate method.
A little late to this discussion...
Restating the obvious: all ARs should have staked keys. Any gas leakage in the system will typically result in failures to extract and/or feed.
I bought a Bushmaster several years ago that had the AK brake, A2 upper - I forget the model. It ran great for a while, then I started getting extraction failures. After some troubleshooting (and tossing a mag in a stock tank), I discovered that the carrier key screws weren't staked - a factory boo-boo. Sent it back for a warranty fix, and all was well.
jr
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Bolt carrier key screws on my two Oly uppers are staked.
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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.
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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.
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OK, Makes sense now ;D
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Well, like my friend just said after sending me an email but forgetting attach the picture... Oooopsie!
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;D
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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.
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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.
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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? :-\
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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. ;D I wouldn't torque it any tighter and risk stripping the threads unless I see a manual that reccomends higher torque.
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Read an article recently that said the majority of Scope problems resulted from over tightening.
I agree with Frank, go by (or buy ;D ) the book .
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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. ;D I wouldn't torque it any tighter and risk stripping the threads unless I see a manual that reccomends higher torque.
Cool. I shoot my N4 as is. Hasn't failed me yet.
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Read an article recently that said the majority of Scope problems resulted from over tightening.
I agree with Frank, go by (or buy ;D ) the book .
Tom, about 24 hours ago you had no idea what we were talking about here.... :o
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That's true. But I expect gun magazines and their writers to know more about a 50 year old design that they've reviewed over and over again. I almost said respected gun magazines. ;) Next they'll be telling us about a new M1911A1 that has some kind of new-fangled feature like a grip safety. ::)
Once upon a time, I'd have agreed with you...
Having worked in the gun industry, government and private training sectors, I've had ample opportunity to examine what is written and how accurate it is. I've had the fortune to be on the same range, and survive unscathed, with some of these gun writers.
It is stunning the amount of technical errors seen in gun magazines. Even such as the American Rifleman can be prone to technical mis-cues.
Take a gun magazine with a grain of salt. If they don't have advertising so as to appear impartial, it won't mean they don't make mistakes either. Due diligence is required to make an informed purchase. Forums like this can help toward that effort.
Proper staking of the the bolt carrier gas key to the bolt carrier goes a long way to insure reliability. Poor or scant staking can result in problems. Many manufacturers realize that most owners won't shoot their rifles enough to really detect a difference, until the key is loose enough to allow gas to leak.
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Tom, about 24 hours ago you had no idea what we were talking about here.... :o
I knew what you were talking about, I was just applying it to the wrong part. Nomenclature fart ;D