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Originally Posted By AZCOP: I see it all the time. Castle Nut torque value is inadequate. Staking is hit and miss. Had a lot of barrels fall off? Cuz that meets barrel spec as well... |
"Major, with the weapon shops out of the way we can introduce steadying laws that could not be flouted." -A.E. Van Vogt 1951
| I got the chance to remove a Smith & Wesson factory installed carbine buffer tube a couple weeks ago. The end plate was staked in 2 places, but it was pointless staking that only served a purpose as witness marks. The castle nut was way under torqued and came off too easily. Also, no grease was present on the threads. So there was no possibility that it was ever torqued to spec and I could imagine it coming loose eventually if it was ever shot enough. |
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Originally Posted By 556Cliff: I got the chance to remove a Smith & Wesson factory installed carbine buffer tube a couple weeks ago. The end plate was staked in 2 places, but it was pointless staking that only served a purpose as witness marks. The castle nut was way under torqued and came off too easily. Also, no grease was present on the threads. So there was no possibility that it was ever torqued to spec and I could imagine it coming loose eventually if it was ever shot enough. The Gov. assembly drawings that were/are online doesn't show any grease or lube that I can find other the light oil that is required for corrosion protection after the finish from manufacture of the locking plate and castle nut. Some of those type oils dry after a while and do not even stay wet. Never understood why the TM's showed it when the assembly drawing in the beginning doesn't seem to require it. The one Colt factory rifle length tube I removed from a gun did not have any type of lube and made a popping sound loud enough when it came loose I thought something had broken. |
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I had one come loose some years ago. No idea on torque but I would have appreciated them spending the extra 30 seconds to stake it at the factory. I still fail to understand the dislike of staking. Seems more like coping to me to argue against it. Checking torque on it takes just as long as staking it. |
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Originally Posted By j3_: The Gov. assembly drawings that were/are online doesn't show any grease or lube that I can find other the light oil that is required for corrosion protection after the finish from manufacture of the locking plate and castle nut. Some of those type oils dry after a while and do not even stay wet. Never understood why the TM's showed it when the assembly drawing in the beginning doesn't seem to require it. The one Colt factory rifle length tube I removed from a gun did not have any type of lube and made a popping sound loud enough when it came loose I thought something had broken. Originally Posted By j3_: Originally Posted By 556Cliff: I got the chance to remove a Smith & Wesson factory installed carbine buffer tube a couple weeks ago. The end plate was staked in 2 places, but it was pointless staking that only served a purpose as witness marks. The castle nut was way under torqued and came off too easily. Also, no grease was present on the threads. So there was no possibility that it was ever torqued to spec and I could imagine it coming loose eventually if it was ever shot enough. The Gov. assembly drawings that were/are online doesn't show any grease or lube that I can find other the light oil that is required for corrosion protection after the finish from manufacture of the locking plate and castle nut. Some of those type oils dry after a while and do not even stay wet. Never understood why the TM's showed it when the assembly drawing in the beginning doesn't seem to require it. The one Colt factory rifle length tube I removed from a gun did not have any type of lube and made a popping sound loud enough when it came loose I thought something had broken. I've heard about grease not being called for in the Gov't assembly drawings before and it's an odd discrepancy. I'm not sure what exactly is "correct" myself, but I've always torqued the castle nut with moly grease/paste since the tech manuals called for it. I've never seen any grease on the threads of Colt carbine buffer tubes when I've disassembled them either (which I thought was odd). I never had them make a popping sound though (probably wouldn't happen if it was greased). I have had a loud "squeak" on certain occasions... Once when removing a rifle buffer tube that had an improperly machined shoulder that galled against the lower (it was greased, but didn't prevent it). Also, on loosening a barrel nut during the installation process on which I forgot to grease the barrel extension flange... Still kicking myself for that one. 
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That argument whether staking is "necessary" is valid but consider this..... if the buffer tube were to start to unscrew itself the stock would spin with it. Anyone knowledgable enough to know about staking is going to instantly know what's going on if the stock is suddenly crooked, and how to remedy it. Even if it's the apocalypse and you can't get the proper wrench hand-tight would do till you could find some pliers. The only time this is a problem that would cause a stoppage before you notice and fix it would be if the buffer tube is just barely holding the buffer retainer detent in place and a slight unscrewing of the buffer tube causes it to come out and start bouncing around inside the gun. I've never had one come loose and I doubt mine are even properly torqued, let along staked. That's including one I had a bumpstock on. |
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Originally Posted By ClangClang: Interestingly, KAC is the only manufacturer that I'm aware of that intentionally does NOT stake their castle nuts - they say it's not necessary on their integrated system. So far, I believe them. Perhaps KAC changed their design since I bought mine in 2012, but mine APPEARED to have a standard castle nut and buffer tube. I never took it off to examine it though. I'm not arguing or disagreeing with you, just saying MINE looked like a mil-spec castle nut. FYI while KAC's are incredibly smooth guns and the barrels are stunningly accurate for what they are, I don't think they are all they are cracked up to be. Mine's ejector spring broke at 4000 rounds and the firing pin seemed to have a metallurgy problem. The tip chipped slightly (still fired fine) and was developing a concentric groove where the flange on the firing pin contacts the Tain of the bolt. Also the snug fit between the bolt's tail and the inside of the carrier that forms the rear gas seal (front seal is the gas rings) was messed-up. It developed big chunks of carbon buildup in the carrier near where the hammer hits the firing pin, which suggests to me that snug fit was not round, rather slightly oval in shape. |
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| I've seen them come loose, but I can't speak to whether they were "properly' torqued. never happened to one of my rifles thoguh |
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Originally Posted By SnowCharger: That argument whether staking is "necessary" is valid but consider this..... if the buffer tube were to start to unscrew itself the stock would spin with it. Anyone knowledgable enough to know about staking is going to instantly know what's going on if the stock is suddenly crooked, and how to remedy it. Even if it's the apocalypse and you can't get the proper wrench hand-tight would do till you could find some pliers. The only time this is a problem that would cause a stoppage before you notice and fix it would be if the buffer tube is just barely holding the buffer retainer detent in place and a slight unscrewing of the buffer tube causes it to come out and start bouncing around inside the gun. I've never had one come loose and I doubt mine are even properly torqued, let along staked. That's including one I had a bumpstock on. No, the buffer tube (receiver extension) can indeed rotate a fair amount and the rifle will still function 100% no problem. I have never seen the buffer retainer come loose on a gun having this issue. Keep in mind that the stock is now rotating maybe 10 or 15 degrees each direction, not unscrewing a half turn or a full turn. So the stock is crooked as hell, but not upside down or anything that obvious. It causes the steel end plate to chew the hell out of the aluminum buffer tube. Typically you might see it chew up the aluminum a half inch on each side. Where I have seen this happen was always un-staked factory guns- a whole lot of Bushmasters, and an Olympic that I owned (before I was an armorer). Bushmaster was so crappy on their assembly that as a preemptive measure we started to check every nut. Then we started installing replacement end plates with sling loops. Degreased everything, loctited, and re-assembled. Once in a while they would loosen up again, usually not noticed until an instructor/armorer would look at the gun at the range. Most AR shooters don’t know shit about staking. Shooter would usually say “oh yeah it has been loose for a while…” FFS… We were dealing with batches of rifles 10 or 15 at a time, brand new from the factory. If other folks have never seen any loosen up I don’t know what to say- they were not being bounced around in cars daily like ours were I guess. Meanwhile I never saw a properly staked nut come loose and allow a stock to rotate. Colt’s never had a similar issue. This was not the only area where Bushmasters were clearly inferior to Colts either. Saw rust underneath the front sight many times. Also they were not using F marked FSB’s, and we did have a few that would not zero vertically as a result. Plus their A3 clamp on handle was not the same height as a standard mil spec one. (Probably because they were not using the F marked FSB’s, I don’t recall exactly). Stocks broke more easily as well, probably more that I can’t think of off the top of my head… |
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