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Posted: 4/9/2008 1:15:29 PM EDT
Introduction:
This is a Dummy's guide to field stripping an HK-54/HK-94 type rifle, and is likewise applicable to HK-91s. I'm including a ton of pictures for reference. The rifle depicted in this guide is a Coharie Arms CA-94 SBR. It has an ambidextrous, pictogram (Safe-Semi) style lower. If there are any differences in disassembly between this and other trigger groups, please feel free to add or make corrections. I am no expert. I will not be covering hammer-spring replacement, or replacement of other parts, simply because I did not replace anything else. Table of Contents: Separated by post 1. Disassembly a. Furniture and Moving Parts Assembly b. Trigger pack removal 2. Part Replacement a. Extractor & Extractor spring b. Ejector & Ejector spring 3. Reassembly a. Trigger Pack b. Bolt-carrier group 4. Additional information |
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Additional Information
Here are some links I've found that will give you some additional info, and, of course, more pictures. HK101 Excellent General FAQ. Includes information on Part replacement, how-to headspace, and a bunch of other stuff. Thanks Osprey! HK-91 Detailed Disassembly This includes disassembly of rear sight. H&K Trigger group disassembly Terrific resource. Includes information on complete trigger group disassembly. Burst pack removal Info on how to remove a burst-type trigger-pack. SEF type trigger group information and removal G3 Schematic Full schematic of a G3, with labels. HK MP5 Operator's Manual Excellent manual, hosted by yours truly. PDF format. File size: ~5MB G3 Armorer's Manual HK-94 Manual G3 Manual This concludes the tutorial. I hope this helps! If there's enough interest, I'll see if we can get this stickied. |
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By the way, I haven't yet shot the rifle with the new parts. I'm hoping to go to the range after work on friday.
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Best of the best!!!!!!!!!!!!!!!!!!!!!!!!!
One of the best threads I've ever seen in my 15yrs gun collecting years.... |
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Wow, thanks!!!! Very impressive. I have read how to do this and that, but the pictures are very helpful. Now I have the confidence to replace the extractor. Thanks again,
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Job well done. Lots of great pics and info. Thanks for taking the time to do
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Some parallel info here also --> HK101
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Requested tack from brouhaha via IM.
Also requested for this thread to be left unlocked if possible, so that we may continue to edit and contribute to it. ETA: Tacked Hopefully people will still read it |
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Range report? Before and after? |
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Range Report (Before the fact):
This is a link to the original range report of the weapon. That was before I started having malfunctions. Malfunctions started at about 1,000 - 1,500 rounds probably. The frequency of the malfunctions rose with the round count, most likely due to increased wear on the extractor spring. Sometimes they would happen: www.youtube.com/watch?v=5AradDtVX-A Sometimes they wouldn't www.youtube.com/watch?v=7gNMVg-qIHo Notice the ejection pattern like I was discussing earlier. Compare it with the new videos.\ Hope this helps! |
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Your ejection pattern is much better, well worth the extra $$ to add reliability. Mine would FTE about 5% of the time before I swapped out the ejector with original HK. Well done post!
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Very nice. One thing to remember if you have an MP5 with a burst lower: when you reassemble the ambi selectors, the lever must be rotated conter-clockwise (when viewed from the left side).
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Uhh, bad news.
Anyone else have broken links for every picture? Who can host them? |
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Yeah, his server hit a snag and he's working on getting them back up ASAP. Maybe I can whip up some MSPaint versions EDIT: Just realized this was my first post. Man, I guess I should have made it something better since I've been lurking for a long time. |
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Dang, could you please fix the links. I need to do the mods myself, thanks.
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Server where the pics are hosted is down for a few days. I'll reply when they're back up
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Yes. I'm in the process of switching servers, so everything is being moved over. They'll be back up soon
ETA: Transfer is finished. Everything working, except I have Deej's avatar throughout the whole thing |
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Thanks. I have an HK MP5 conversion and extra parts for about any situation, so this will get printed off and stored in my parts kit! I don't yet have an amourer's manual, so this will really be helpful. I bought the upgraded firing pin spring and newer extractor springs and wasn't sure how I was going to install them if I ever need to.
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Quoted: Thanks. I have an HK MP5 conversion and extra parts for about any situation, so this will get printed off and stored in my parts kit! I don't yet have an amourer's manual, so this will really be helpful. I bought the upgraded firing pin spring and newer extractor springs and wasn't sure how I was going to install them if I ever need to. Glad I could help! You can find the G3 Armorer's Manual here |
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Question. I have a CA 89 SBR and as others have reported I see a small, but still annoying, amount of FTEs. My concern is that CA has tweaked and tested the gun to work on their parts. If one swaps out critical parts like the extractors and levers, doesn't that throw everything else off?
Yes, the HK parts are superior but are they guaranteed to make the clone work better? Just want to know before I drop down more $ on hkparts.net for genuine HK parts. thanks |
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Failure to extract or failure to eject?
As far as I know, Coharie hasn't changed any parts to where they are non-compatible. Only cheaper to produce. If you're having failure to extracts, I would just start with an HK extractor (I can't imagine them changing spec for this item, anyway). Hell, if you're having ejection issues I'd still start in the same place. Approximately how many rounds through the rifle? From my observations, extractor springs are the number one cause of issues in these rifles. As you can see from the OP, they are fairly weak and are prone to malformation. Failure rates seem to pop-up or increase substantially around 1k+ rounds from my observations of other posters and the experience of my own. IIRC It's only an $8.00 or so part, and I recommend always trying the cheapest solution first |
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Quoted:
Failure to extract or failure to eject? As far as I know, Coharie hasn't changed any parts to where they are non-compatible. Only cheaper to produce. If you're having failure to extracts, I would just start with an HK extractor (I can't imagine them changing spec for this item, anyway). Hell, if you're having ejection issues I'd still start in the same place. Approximately how many rounds through the rifle? From my observations, extractor springs are the number one cause of issues in these rifles. As you can see from the OP, they are fairly weak and are prone to malformation. Failure rates seem to pop-up or increase substantially around 1k+ rounds from my observations of other posters and the experience of my own. IIRC It's only an $8.00 or so part, and I recommend always trying the cheapest solution first sorry, I meant failure to eject, the mangled casing gets stuck in the chamber halfway on its way out crushed by the bolt. Gun is brand new, maybe 300rnds through it. You're right, for $10 it's worth a try. Is hkparts.net the best place to buy? They are out of stock on the extractor itself. thanks for the insight |
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To be honest, I'm not so sure you need to replace the actual extractor. I just did because, hell why not.
Adam Webber at HKparts and Gordon Miller at hkspecialiststore.com are both top notch |
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Most likely culprets in no particular order:
Extractor spring extractor bolt head (Is it in spec/oversixed? does it pass the zip tie test?) ejector (is there much side to side play?) trigger housing (is it parallel to the receiver or is the rear of the housing higher/lower creating an angle?) –––––––––––––––––––––– I bought a used Coharie SBR w/ the S/N under 100. I knew it had problems before I bought it, when I demo'd it b4 buying, but the price was right. It failed to eject 2-3 times per mag and jammed up the pack, and those that did eject, just dribbled out. i had no idea if was in the lower (ejector, pack angle, etc) or the upper(extractor, bolt, headspace, carrier/recoil rod). I replaced the ejector w/a factory one and that didnt fix it, My plan was to go to the range and start swapping parts w/a friends clone to diagnose or at least narrow down the problem bewteen upper or lower. 1 thing I knew was right: the bolt held the case tightly and passed the ziptie test. 2 things I knew were wrong: the ejector had alot of side to side movement, the trigger pack angle was not parallel to the receiver. I ended up buying a factory SEF lower and this thing now runs like a top. It ate everything from blazer brass to the "supposidly weak" WWB. Good luck. It may take some time/aggrivation, but it is worth it. I now have 900.00 in mine w/the HK FH and SEF trigger pack (semi, SBR) and am very pleased w/it. |
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I would put the Coharie mags very high on that list, too. They're pretty big piles of shit
What is the zip-tie test? |
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Quoted:
I would put the Coharie mags very high on that list, too. They're pretty big piles of shit What is the zip-tie test? http://www.youtube.com/watch?v=FJg1G0UBO5c |
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Never updated new credit card information for the domain name service and it was bought after it expired. Working on a fix...
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Well, that was a nightmare of trying to remember FTP passwords from 9 years ago but everything is back up and working now. Should be a permanent fix.
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Quoted:
Link to HK91 disassembly information isnt working. View Quote https://web.archive.org/web/20090129145200/http://home.att.net/~j.p.george/HK91.htm The HK101 link is bad too, but it is almost a decade old |
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Quoted:
That is probably not the OPs site and thus no control over it...BUT, the link data seems to be archived and could be grabbed if someone else had somewhere to host it https://web.archive.org/web/20090129145200/http://home.att.net/~j.p.george/HK91.htm The HK101 link is bad too, but it is almost a decade old View Quote View All Quotes View All Quotes Quoted:
Quoted:
Link to HK91 disassembly information isnt working. https://web.archive.org/web/20090129145200/http://home.att.net/~j.p.george/HK91.htm The HK101 link is bad too, but it is almost a decade old |
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