View Full Version : Sheared extractor
Saw an AR tonight that sheared off not one but two extractors. AR was a Rock River, marked 5.56 but presumably actually .223, owned by a good shooter and shot quite bit. Had a malfunction, turned out to be a sheared extractor. Borrowed a BCG from another shooter and did the same thing to that extractor. Borrowed BCG had a BCM extractor.
The shooter is going to go home and clean it, and come back next week so we can drop Ned's .223/5.56 gauge in the chamber and see what's what.
Any other thoughts?
Rob,
Can you post some pics? Two in one day is just crazy. What type of ammo was he shooting? My guess is that thing is really tight.
Saw an AR tonight that sheared off not one but two extractors. AR was a Rock River, marked 5.56 but presumably actually .223, owned by a good shooter and shot quite bit. Had a malfunction, turned out to be a sheared extractor. Borrowed a BCG from another shooter and did the same thing to that extractor. Borrowed BCG had a BCM extractor.
The shooter is going to go home and clean it, and come back next week so we can drop Ned's .223/5.56 gauge in the chamber and see what's what.
Any other thoughts?
I wanted to add that the loaned BCG is mine. It is from BCM, and ran like a top in the LMT 10.5" upper that I got from them too. I have about 3K through my 10.5" gun. Lube it generously and shoot Factory Xm193 or Hornady TAP 60 gr.
I do not know what ammo the other guy was using, but as Rob stated above this guy is a good shooter and shhots quite a bit with this gun.
I could not tell what was happening. But, I will be calling BCM to order a new extractor or two or three tomorrow.
ANY input or ways to make sure this stops is appreciated.
I think Rob got some pics of the extractors...
Jack
I'll post pics later today assuming they come out.
Robb Jensen
07-29-09, 06:13
It also sounds to me like a tight chamber. I find that the reamer will always remove material from RRA barrels. The RRA owner might also want to use an H or H2 buffer to slow bolt velocity down.
Robb, any thoughts on why the problem would just show up now, and when it did show up it appears to be chronic? this guy shoots with us a lot, does the matches and the drills, has taken at least one class maybe more from jackinfl, and AFAIk it's all been with this carbine with that BCG. If it had only happened to his original extractor I would have just chalked it up to being worn out, but to do it to another right after it makes me wonder if something in the gun hasn't changed to cause it to shear extractors.
Tuesday I'll drop the checker into it, and we'll verify ammo used, buffer, and we'll replace it with a brand new BCM extractor and see if it still has the same problems. I'll also bring a couple of other buffers so we can swap his out.
pics, which are not so great. Tried to show the pics unretouched and with a red line indicating the shear point. Pics of second extractor didn't come out so good and don't really show anything. I'll try to swap Jack a new BCM for his sheared one.
http://i134.photobucket.com/albums/q111/rob_s/gun%20stuff/kblank.jpg
http://i134.photobucket.com/albums/q111/rob_s/gun%20stuff/kmarked.jpg
http://i134.photobucket.com/albums/q111/rob_s/gun%20stuff/kblank2.jpg
http://i134.photobucket.com/albums/q111/rob_s/gun%20stuff/kmarked2.jpg
Robb Jensen
07-29-09, 07:33
I'm thinking the gas port may have eroded open enough (and RRA are already pretty big) to cause this gun to cycle too fast and might be causing this.
If you can easily remove the gas block or FSB check the size of the gas port.
I was kind of wondering that myself. Especially if he has put lots of rounds through it like Rob says. Combine that with a potentially tight chamber (pretty sure the RRA ones are not true 5.56) and I can see how it would happen. I would be tempted to try an H2 buffer to see what happens for S&G.
I'm thinking the gas port may have eroded open enough (and RRA are already pretty big) to cause this gun to cycle too fast and might be causing this.
If you can easily remove the gas block or FSB check the size of the gas port.
How is the gas port measured? Interior dimensions with the dial caliper? What are the szie ranges for "in spec"?
By the way I asked the shooter how many rounds and he said 120K. But this was a quick off the cuff comment... I have known him for a few years and this is the gun he uses.
One point, but I do not think it is directly related tot he extractor, but a year ago at a class upon inspecting his gun I found that his ejector had very litttle spring tension. I pulled it out and the spring was broken in two pieces.
Jack
Thanks.
Will see what we can get done on Tuesday and will report back.
Here's the shooter in question, proving that slow and steady wins the race. Despite having a catestrophic malfunction with the carbine, the shooter that finished first failed to neutralize a target, and the shooter with the malfunction was able to clear his issue and finish the stage.
Ironically, it was the shooter in gray that helped him clear it. :D
http://i134.photobucket.com/albums/q111/rob_s/SFDCC/090728%20SFDCC/th_090728STAGEONE011.jpg (http://s134.photobucket.com/albums/q111/rob_s/SFDCC/090728%20SFDCC/?action=view¤t=090728STAGEONE011.flv)
Did you mean 12K? 120K is hard to believe. If it is 12K he probably needs to look at an overhaul and inspection to include some gaging. I would say minimum headspace and firing pin protrusion since I know the other gages are a PITA to locate.
How is the gas port measured? Interior dimensions with the dial caliper? What are the szie ranges for "in spec"?
By the way I asked the shooter how many rounds and he said 120K. But this was a quick off the cuff comment... I have known him for a few years and this is the gun he uses.
One point, but I do not think it is directly related tot he extractor, but a year ago at a class upon inspecting his gun I found that his ejector had very litttle spring tension. I pulled it out and the spring was broken in two pieces.
Jack
OldNavyGuy
07-29-09, 09:31
just from what i can tell by the photos, inspect the barrel extension, it appears the extractor is slamming into something upon closing, not from ejecting.
photos can sometimes be misleading.
I would say look at ammo first (including chronograph if you can) and then give the chamber a good reaming before you go ripping the gun apart and measuring it. Does the shooter clean the chamber? Maybe the combination of a tighter chamber and thousands of rounds worth of crud finally stacked up?
Do you have any of the cartridge cases from the gun from just before it sheared the extractors? Any clues on those? Usually you can see signs of overpressure (e.g., flattened primers), "overgassed" (case rim gets noticeably mangled by extractor). If you have excessive headspace - and I doubt that's the issue here - you'll see signs of case head separation or stretch near the back of the casing.
Did you mean 12K? 120K is hard to believe. If it is 12K he probably needs to look at an overhaul and inspection to include some gaging. I would say minimum headspace and firing pin protrusion since I know the other gages are a PITA to locate.
If it had 120K through it I bet this would not be the only issue it is having!
I'll be interested to hear what is going on with his carbine.
Spooky
Robb Jensen
07-29-09, 11:42
How is the gas port measured? Interior dimensions with the dial caliper? What are the szie ranges for "in spec"?
By the way I asked the shooter how many rounds and he said 120K. But this was a quick off the cuff comment... I have known him for a few years and this is the gun he uses.
One point, but I do not think it is directly related tot he extractor, but a year ago at a class upon inspecting his gun I found that his ejector had very litttle spring tension. I pulled it out and the spring was broken in two pieces.
Jack
I used drill bits using the one that fits the best the mic the drill bit. But you can eyeball it with a micrometer and be pretty damn close if not seeing which drill bit fits the best. You'll need fraction sized drill bits, and numbered drills. 120K would have some serious port erosion and probably bad throat erosion as well.
120K would have some serious port erosion and probably bad throat erosion as well.
I would think that may be an issue, even at 12K. I believe RRA's are a reasonable quality arm for the money. But their barrels are 4140, not the harder milspec steel. Even with chrome, the erosion would seem to be a very decent possibility, if not probability. Personally, I fully expected to replace my RRA barrels after 10K or thereabouts.
Rob_S
By the way letting him beat me after that I had to FIX his gun was and is BS. I am wining like a little girl. Videos make me look fat! Ok, I am fat.
GotM4,
Measuring with a drill set is a good idea. WHat are the specs to look for?
Thanks,
Jack
I've seen a broken extractor like that once, on a Spikes upper using some reloads a friend supplied. At first we just had a few extraction issues, but after a few rounds my rifle (a Bushy) had 2 or 3 Fail to Extracts, and his rifle (the Spikes) broke the extractor.
It turned out that he had set the crimp stage wrong on his reloading press (Dillon 650xl) and it had lightly mushroomed the neck of each rifle case (not enough to see the problem, unless you knew it was there)
I also had a tight chamber on another gun, and while it didn't break the extractor, the gun acted similar to what we experienced that day with the bad reloads. I just fixed that gun today using Ned's 5.56 reamer (very nice tool, worth the money)
I don't know if that helps your situation at all, but figured I'd contribute.
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