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Posted: 3/17/2016 6:46:58 PM EDT
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It's time for everyone's favorite game. . .
Dumb Question Time! The AR15 Bolt, we all know it well. It's got lugs around the chamber end to lock into the lugs on the barrel extension, which keeps the bolt in place until the bullet has passed the gas port, which then pushes the Carrier backwards, rotating the bolt in place, and finally freeing the bolt. That all makes sense to me. However, I am confused by something relatively minor. There are 7 lugs that have flat areas on the back, which lock into the lugs of the extension. There is ALSO, one lug, which is shorter than the others, and has angles on the front and back sides, such that it does NOT lock into anything. That lug is on the Extractor. Why is that lump there? Clearly it's not hurting anything by being there, but it seems like it's also not accomplishing much either? Does it serve a purpose I don't see? I could see it as keeping the extractor from lifting while in the chamber, which would cause FTEs, except that there would still be two lugs from the barrel extension keeping it closed, even if the lug was removed from the extractor itself. 
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Well, if you change the angle on it, it will change the ejection pattern. You can do this to help lefties, making the rifle eject to two-o'clock instead of four or five. I'll see if I can find the pic for you.
Here you go: I was wrong - it's on the ejector itself. Been a long week. 
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Quoted:
HA! No worries, Morg. I originally said "Ejector" throughout the original post (and title) even though I'm talking about the "Extractor". . . Yeah - I get dumb about nomenclature (as you can see) when I get tired. It's been a rough week... I was mixing up the two also. |
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Quoted: Re-enforcement of the extractor lip. |
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Quoted: Not a dumb question at all. Here is a how it worked photo... This was from a Colt M4 with a catastrophic failure... no barrel bulge, all of it came out the back. Check out the banana peel on the extractor. Ruined the lower too. http://<a href=https://farm2.staticflickr.com/1706/25788417341_29f63d40f3_c.jpg</a>IMAG0780 by Deer Hunter, on Flickr" /> http://<a href=https://farm2.staticflickr.com/1664/25883366545_7604e1cf07_c.jpg</a>IMAG0779 by Deer Hunter, on Flickr" /> http://<a href=https://farm2.staticflickr.com/1521/25883368085_c3ed992c81_c.jpg</a>IMAG0781 by Deer Hunter, on Flickr" /> Quoted: Quoted: Re-enforcement of the extractor lip. http://<a href=https://farm2.staticflickr.com/1706/25788417341_29f63d40f3_c.jpg</a>IMAG0780 by Deer Hunter, on Flickr" /> http://<a href=https://farm2.staticflickr.com/1664/25883366545_7604e1cf07_c.jpg</a>IMAG0779 by Deer Hunter, on Flickr" /> http://<a href=https://farm2.staticflickr.com/1521/25883368085_c3ed992c81_c.jpg</a>IMAG0781 by Deer Hunter, on Flickr" /> |
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Quoted:
Not a dumb question at all. Here is a how it worked photo... This was from a Colt M4 with a catastrophic failure... no barrel bulge, all of it came out the back. Check out the banana peel on the extractor. Ruined the lower too.http://<a href=https://farm2.staticflickr.com/1706/25788417341_29f63d40f3_c.jpg</a>IMAG0780 by Deer Hunter, on Flickr" /> http://<a href=https://farm2.staticflickr.com/1664/25883366545_7604e1cf07_c.jpg</a>IMAG0779 by Deer Hunter, on Flickr" /> http://<a href=https://farm2.staticflickr.com/1521/25883368085_c3ed992c81_c.jpg</a>IMAG0781 by Deer Hunter, on Flickr" /> Quoted:
Quoted:
Re-enforcement of the extractor lip. http://<a href=https://farm2.staticflickr.com/1664/25883366545_7604e1cf07_c.jpg</a>IMAG0779 by Deer Hunter, on Flickr" /> http://<a href=https://farm2.staticflickr.com/1521/25883368085_c3ed992c81_c.jpg</a>IMAG0781 by Deer Hunter, on Flickr" /> Ooof! 
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Liv4Nov!
Did that happen to you? If so, any harm to self? I think I see what happened! Case seperation? Factory ammo or reload? Sure made a mess of that BCG. Kinda makes me a little paranoid, shooting mostly reloads, being a lefty and all. My friend died this past winter who had a M-16 blow up on him in basic training in 60's. Cost him an eye and two fingers but kept him out of VN. He was always kinda grateful and thought he had been looked out for from above. Barrel was clear on that one also. Day my chrono was reporting well over 3000 FPS with I'm pretty sure 68 grain HPBT, had me a little nervy. Primers and cases looked fine. Thought I was under recommended max service rifle load data powder charge but I was easy 200 FPS over what Hornady 7 said it would be too. Probably took some life off the barrel with those. Don't remember if I pulled them or tossed them in the pond. .223 case won't hold but so much powder so generally a built in fail safe with anything but the finest fast burn stuff and I wasn't using that. Could have been the chronograph but generally it's dead on with the load manuals.. OOOOOFFF! |
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Quoted:
Not a dumb question at all. Here is a how it worked photo... This was from a Colt M4 with a catastrophic failure... no barrel bulge, all of it came out the back. Check out the banana peel on the extractor. Ruined the lower too.http://<a href=https://farm2.staticflickr.com/1706/25788417341_29f63d40f3_c.jpg</a>IMAG0780 by Deer Hunter, on Flickr" /> http://<a href=https://farm2.staticflickr.com/1664/25883366545_7604e1cf07_c.jpg</a>IMAG0779 by Deer Hunter, on Flickr" /> http://<a href=https://farm2.staticflickr.com/1521/25883368085_c3ed992c81_c.jpg</a>IMAG0781 by Deer Hunter, on Flickr" /> Quoted:
Quoted:
Re-enforcement of the extractor lip. http://<a href=https://farm2.staticflickr.com/1664/25883366545_7604e1cf07_c.jpg</a>IMAG0779 by Deer Hunter, on Flickr" /> http://<a href=https://farm2.staticflickr.com/1521/25883368085_c3ed992c81_c.jpg</a>IMAG0781 by Deer Hunter, on Flickr" /> What was the ammo? Cause? Almost looks like a headspace issue. |
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Yes, the extractor spine lug helps prevent the lip from breaking off, as long as the metallurgy is good.
There are a lot of dimensions on the extractor that get overlooked, in addition to that. The relief cuts along the edges that ride in the extractor pocket on the bolt, which remove the fangs on the edges of the extractor lip, are another one. A lot of imitation extractors don't even bother with that cut. Also, the angle on the front of the extractor that helps it snap over the case rim, that gets overlooked. Tool steel and heat treatments for extractors are very critical for a reliable gun. |
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I don't remember all the details, but I do remember we related it to the ammo lot which was reported as LC stamped M855. I saw this similar situation more than once with Federal Frangible ammunition. There did not appear to be any barrel bulges from what I remember, and the bullet did exit the barrel. We could not headspace it as the casing was fused to the chamber. We were told the shooter was only one mag into firing but I didn't buy it at the time. As you can see everything went the wrong way and unlocking never occurred. The extension split, and everything peeled back. What I got a chuckle out of at the time was the Proof stamp. The shooter was not injured.  IMAG0788 by Deer Hunter, on Flickr" /> |
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Glad no one was hurt. I purchase or am given a lot of range brass USGI, LEO etc from all over the USA. Lately I've been noticing much more with damaged rims. Probably 10% of what I get fails first visual inspection. Not really related to separated case issue but there is something wrong with some of the US brass mfg today IMO. Quality control or something.
Most has been 2013 headstamp and newer. Mostly FC stamped but I believe they own LC. Not uncommon with LC either just not as much. About all I even get now days. Amazes me that there are actually two different styles of brass being produced. The FC we know from cross section that it is thinner than LC in primer pocket area. A couple warm firings and the primers will fall right out of pocket too. I always figured it was an ammo conspiracy but in reality just a bunch of bean counters saving a few coins more than likely. Gonna whine like babies when they get the crap sued out of them for being a bunch of cheap A$$ MF's too. FC NATO stamp is much better than non nato stamped for reloading IMO. FC stamp is always way short and thin. OP Issue could have something to do with extractor or spring used today but I've never experienced anything of the sort firing from any of my AR platform weapons ( mostly with older Colt / FN or Young Mfg BCG components). Have stuck a case or two in my day from lack of lube IMO and did kinda the same thing to the cartridge rim in the die. Still looks ammo related to me. Gonna be hard to check headspace on that one. Again thanks for sharing. Kinda makes me want to be even more careful with case inspection. I know most every load manual warns of case separation and it's potential dangers. Pic of case probably middle of the road. Some worse and some not as bad. Most I squish immediately and scrap. 
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Quoted: Glad no one was hurt. I purchase or am given a lot of range brass USGI, LEO etc from all over the USA. Lately I've been noticing much more with damaged rims. Probably 10% of what I get fails first visual inspection. Not really related to separated case issue but there is something wrong with some of the US brass mfg today IMO. Quality control or something. Most has been 2013 headstamp and newer. Mostly FC stamped but I believe they own LC. Not uncommon with LC either just not as much. About all I even get now days. Amazes me that there are actually two different styles of brass being produced. The FC we know from cross section that it is thinner than LC in primer pocket area. A couple warm firings and the primers will fall right out of pocket too. I always figured it was an ammo conspiracy but in reality just a bunch of bean counters saving a few coins more than likely. Gonna whine like babies when they get the crap sued out of them for being a bunch of cheap A$$ MF's too. FC NATO stamp is much better than non nato stamped for reloading IMO. FC stamp is always way short and thin. OP Issue could have something to do with extractor or spring used today but I've never experienced anything of the sort firing from any of my AR platform weapons ( mostly with older Colt / FN or Young Mfg BCG components). Have stuck a case or two in my day from lack of lube IMO and did kinda the same thing to the cartridge rim in the die. Still looks ammo related to me. Gonna be hard to check headspace on that one. Again thanks for sharing. Kinda makes me want to be even more careful with case inspection. I know most every load manual warns of case separation and it's potential dangers. Pic of case probably middle of the road. Some worse and some not as bad. Most I squish immediately and scrap. http://i866.photobucket.com/albums/ab223/cndenmark/DSCN2366_zps2qw5s61r.jpg |
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