Maybe just buy an MP5-E Bolthead... but in the mean time!
Hello fellow purse wielders!
Writing up this little gem for those of you that like me, prefer to know why your shit ain't working, rather than buying/swapping out a bunch of parts hoping it will suddenly start working. Sooooo, buckle up chuckle fucks, I like to over-explain shit.
On todays agenda: Extractors.
More specifically, why the cheap ass Turkish clone extractors don't work!
Disclaimer: I'm not a licensed gunsmith, nor am I a lawyer. For all intents and purposes, I'm just a random fucker on the internet. Don't listen to me... or do... up to you, literally. Any and all decisions you make going forward using information from this post, is done so at your own discretion. I didn't tell you do to this, I'm merely telling you what caused my issue and how I fixed it. Use your friggin brain.
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Symptoms: FTE | FTF | 2-3x bullets jammed between mag/bolt/chamber | cases jammed behind trigger.
The problem: Extractor was out of spec.
Elaboration: While fiddling around with my MP5 (MAC5 which hasn't shot more than 3 round straight since the day it landed in my lap) I was playing with the bolt head, knowing that the problem was either going to be the extractor or the ejector. Ejector appeared to clear fine, so I focused on the extractor. Placed a spent 9mm casing into the bolt face to emulate how it would be on a closed bolt. Slipped in fine, cool. Went to remove it, and that's when it all made sense. The casing was practically locked into the bolt face. I really had to pry on it with some actual force just to get it slip back out. When it did, there were two snaggletooth bite marks out of the rim of the brass.
So what's happening, is that as the brass tries to rock out of the extractor, it creates a pinch point between the rim of the brass and where the recess necks back up to the exterior wall thickness. See "Pinch Area" in Picture 1, and in Picture 2 how as the case rocks out, it contacts the top of the extractor, causing the "teeth" of the extractor to bite into the rim of the brass. In 3D software, this is viewed as clipping, but in real life, it's a binding point in the process of the action cycling. One that hinders the ejector from doing it's job effectively and efficiently.
In short, the extractors are extra thiccc. Something something, the clap of their cheeks- alright I'll stop there...
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How I fixed it: Rounding down the points and putting a soft radius on the underside of the extractor "teeth". See Pictures 3, 4, and IRL photos for reference.
In theory, you should be able to achieve this same effect by reprofiling the top of the extractor to have a shallower top/lip so there's less material to get caught in the pinch area as discussed above with Pictures 1 and 2. See picture 5 for example of extractor top/lip reprofile. I, however, did not attempt this approach, so your mileage may vary.
Honestly, all of this makes a ton of sense, when you take a look at an actual HK extractor commonly seen on the various parts sites. The teeth of the extractor look significantly rounded and are likely not as thick in the top/lip area, leading to smooth operation. The "teeth" on my extractor where very sharp and more like spikes/teeth rather than rounded nubs.
The End Result: What "should" be your end result, is a 9mm scapcap/empty casing that sits snug inside the bolt face, but shouldn't require any more effort than a gentle tap in the direction of the extractor to knock it out. If it's still too snug to easily fall out or you have to fight it at all, you likely need to take just a smidgeon more material off to achieve the desired result.
Be careful, as too much removal might result in a misfunctioning extractor, at which point, you'd be just buying a new HK extractor anyways. Soooo, eh? This fix is mostly for those that can't be fucked to throw $35 at a new one and wait for it to get here in the first place.
(Or those that want to KNOW why their shit isn't functioning in the first place.)
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Final recommendation: Be smart, don't modify your guns unless you know what you're doing. If you're unqualified, please seek out a licensed gunsmith to do the necessary modifications. Alternatively, go and buy a RCM MP5-E bolt head. It's a much more robust bolt head and should circumvent this issue entirely, alongside other issues.
Anywho! Have a lovely day and be safe! Until next time!