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Discussion Starter #1 (Edited)
Well I recieved my Hk Mp5 A2 demilled kit 1 week ago. Picked up my ATI MKE 94 Carbine reciever from My FFL's shop and started the project.

I've removed the barrel, trunnion and triple tree, cocking tube and internals , F A bolt and carrier from the demilled kit along with all the other stock hardware.
German Trunnion,cocking tube and barrel I'm saving for a future build.

I stripped the bolt carrier assembly all the way down, inspected the rollers. These were surprisingly low wear stock 8's (7.98mm to be exact).
Extactor and spring,locking piece and firing pin all looked good too ,so all the parts spent some time in my sonic cleaner before re assembly. While that was going on, I trimmed the lower grip for the semi shelf. The ambi selector and the US trigger pack does not allow correct line up with pictographs on the demilled lower, but I'll fix that later.

I am making this thing a carbine first while I'm waiting on my sbr request. So I am proceeding with the rifle build with the 922r required minimum and fake supressor to allow for easy swap to SBR. If I was going pistol I could have saved some $$ since 922r is not necessary on pistols.
These Guns are way more fun shouldered anyway. It will be money well spent.

The reciever already has the paddle release and semi shelf installed. I
Disassembled the demilled guns lower ambi pack and replaced the trigger pack with a Special Weapons US made pack counting towards 4 922r parts.
I recieved my US made 3 lug threaded navy barrel and new oversized pin yesterday . My new sling loop/tree pin and US wide grip showed up with it.
Hoping to push the barrel in and set the bolt gap tonight.
 

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Discussion Starter #4
Yes
I plan to use the German barrel,trunnion and cocking tube for my first flat build.
I also just wanted to try pressing it out for the experience.
So here is today's progress
Barrel pressed
Bolt gap between 17 and 18
End milled,Pinned and blind welded barrel with 5.25mm pin
End milled sling eyelet for the triple tree
Crowned it in place
Cleaned her off and put her together.
Can't wait to see if she sings !!
Here are some pics
Got so caught up with setting the gap,I forgot to take pics.
Had a sweet tool that was milled to fit the in the chamber and fit nicely through the reciever. I even cut marks in it while I was pressing that lined up with the end of the reciever .(One at 30,than 25 than finally at 18.) Should help me with getting the next one close without having to stop ,insert bolt and measure after every few pumps of the handle.
If all goes well with live fire, I'll dress her up in some sexy black ceracote.
 

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Discussion Starter #8
So today I'm pinning my fake supressor and installing all the 922r parts to get this thing finished to 94 carbine lenght til my sbr stamp arrives.
I can't wait to give her a try ,but weather ain't looking good til next week. I'll post pics when I'm done.
 

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Discussion Starter #10
Well went to the range to fire a few test rnds through the gun today.
I was fairly confident she would shoot,but no idea how she'd cycle.
Well first off ,I only had about 30 rnds of mixed ammo.
Put 10 in the mag,let fly the handle,switched to hot and squeezed with nervous anticipation. "Bang" went the first round toward paper,out flew the spent brass.
Good start !!
Pulled the trigger again and....notta,nothin,no click. Looked like the bolt was in battery,hmmm.
Huh,well let's see.Pulled the charging handle back and out came the unfired round with no signs of a problem feeding and no pin mark at all.
Glitch? Been down this road before but fail to fires were way more obvious on the other clones.
OK,let's not panic I tell myself,and slapped her shut for another go.
Pulled the trigger...."bang",again...."bang" than another 5 shots down range.
Okay ,maybe it was stage fright.
Loaded another 10 in the mag and let fly the handle . Squeezed and ....."Bang" ,again... "Bang" ,again...Nope ! Nothing,no click, no jam. Ejected that rnd same situation . I slapped her closed and shot out the rest of the magazine with no hiccups.
Took a look,nothing looked out of place ,loaded in the last bullets and shot through all of them.
Well I guess it was mostly a successful first firing, but the FTF'S had me a little puzzled. Time to tear down inspect and regroup.
I checked the bolt gap. It was still holding at a tight 17 were I set it.
I guess it could have a sticky recoil rod or worn spring since they were off the demilled gun.
It also might be the US trigger pack,but it felt good. The trigger doesn't feel short and the sear locks every time .
As I was fiddle fartin with the trigger something caught my eye.
The ejector lever looked funny at the front contact point.
I picked it up to get a closer look and the damn end fell off in my hand.
WTF ?
Hmmm...was this the cause or just a symptom?
I still had the demilled German lever to look at and noticed right off a difference in construction. It was way beefier where the US one was broken.
Before putting that one on I did some closer looking at the bolt carrier and upper reciever . I did notice the Mke reciever has a large rounded mass which is the back of the ejector port deflector. It runs awful close to the bolt and carrier. I put some red paint on it during the build to see if it was interfering . When I did some bolt drops during gap setting,I saw some contact and fine filed it a bit and repainted.
During inspectin After the test firing, I did see some contacting marks.
Also noticed a little bolt carrier jostling when passing by the "LUMP".
Wonder if this is the cause?
So before I try again ,please feel free to chime in if you've seen,heard of or experienced similar.
I'll post some pics.
I don't want to damage anything so I wanna get this straightened out.
 

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Discussion Starter #11 (Edited)
Here are some pics
2nd pic is the US broken part held in place
Next is the much beefier German part
Next is how it looks with bolt in battery
Last is with the bolt being held at point where I think it contacted bolt and got damaged.
I'm thinking it either was bent or somehow was mis aligned.
Could have been damaged before assembly for all I know.
There is definitely slop in the ejector lever where it rests in the US trigger box. The German one is a perfect fit in its case.
I think my upper reciever needs to have some truing before I mess with the bolt or deflector . May have tweaked it a bit while chucking it up for the end mill.
Anyway,got a little more work to do on it for sure.
Any ideas or help would be very welcome.
 

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Did you say it was a U.S. Carrier or German? Case deflector could be in the wrong spot. One of my first builds I had to file the deflector till the carrier didn't hang up, I started running the deflector a lil higher in the cut out for it, if you run it too low it will hit the carrier.

U.S. Ejector levers usually need filing to make sure they ride correctly in the bolt.
Always run German ejector lever and Hk mag catches.

As long as you have a good gap and the trunnion is not canted, they will almost always fire.
 

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Discussion Starter #13
Bolt carrier assy. is german, upper reciever is Turkish ATI MKE. Fit on these mke parts seem a little off par and need some adjusting to get them in spec.( kinda expected some hurdles)
It does appear to be contacting the bottom of the deflector . It always contacts when im holding the reciever upside down .
Im gonna trim it down,just wonder if I should remove it to really get it shaped and smoothed out.
I am still curious how the ejector could have affected hammer drop.
Ejection was working during the test fire. I'm thinking it may have been the bolt contacting that port lump that caused a few problems.
I put the German gen 3 ejector lever in it this morning. Had to tighten up the lever channel in the trigger box to get the play out. Seems smooth and centered in the bolt groove now.
I also ordered an extra gen 3 lever and new German recoil spring.
Hope these improvements will get her straightened out.
I've heard of using steel bars to true out the reciever. But I guess I just could get the flat jigs and do it. Gonna need them in the future anyway.
 

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Bolt carrier assy. is german, upper reciever is Turkish ATI MKE. Fit on these mke parts seem a little off par and need some adjusting to get them in spec.( kinda expected some hurdles)
It does appear to be contacting the bottom of the deflector . It always contacts when im holding the reciever upside down .
Im gonna trim it down,just wonder if I should remove it to really get it shaped and smoothed out.
I am still curious how the ejector could have affected hammer drop.
Ejection was working during the test fire. I'm thinking it may have been the bolt contacting that port lump that caused a few problems.
I put the German gen 3 ejector lever in it this morning. Had to tighten up the lever channel in the trigger box to get the play out. Seems smooth and centered in the bolt groove now.
I also ordered an extra gen 3 lever and new German recoil spring.
Hope these improvements will get her straightened out.
I've heard of using steel bars to true out the reciever. But I guess I just could get the flat jigs and do it. Gonna need them in the future anyway.
my setup is an old FMP G3 bolt as a mandrel and using the receiver rod and smaller 5/16 I want to say rods that come with the kit.
I don't really see the mke receiver as the issue. If bolt gap is good, I would try a German trigger group. You never know if your using special baileys parts.
 

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Discussion Starter #15
So I put the German mp5 ejector in the trigger group I have on my C93. It's a SEF with German parts that was modified to semi(Bill Springfield built it) .Works perfect in the century so I'm gonna try it.
Also took a little more material off that ejector port to give the carrier more clearance.
I'm gonna try to have someone video the shots to see if it is doing anything funny.
Wish me luck.
I'll give a go tomorrow.
 

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Discussion Starter #17
I may have worded it incorrectly.
The ejector lever is off my demilled mp5 a2 trigger pack.
I just used my trigger group that was on my 93 and swapped the 93 lever for the correct mp5/94 lever.
And the verdict......
10 rnds no hiccups
Anther 10 no hiccups
20 as fast as I could pull the trigger,no hiccups finished the last ten in the mag no problems at all !!!
Not 100% sure if it was the trigger group or the bolt contacting the ejector port. Leaning towards a little of both.
Either way I'm happy to know she's good otherwise. I'll have to throw the other trigger pack in and retest.
I'll know tomorrow.
 

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Discussion Starter #18
Special weapons trigger pack removal seemed to fix the problem.
I tore the pack down to inspect.
I am by no means a gunsmith or machinist ,so forgive the terminology if I'm off base a bit.
Well we know the ejector lever was crap.

The sear looked like original german, including years of grunge stuck to it. Ran it and the hammer in my sonic cleaner to see how bad they werected

I took a closer look at the sear's catch surface and it looks worn with a chipped corner .
Trigger looks fairely new and the contact surface looks to be ok . Edges and surfaces appear sharp and square ,to me anyway.
The hammer looks to be in better shape than the sear but not very new looking. Still the catch surfaces look crisp and square.
Springs all look new
Case looks just OK,but not as square or clean as the Springfield one I had done.
I may try to salvage this pack by replacing the sear with a New US one .
Conclusion.....
This pack was the problem and the quality was sub par.
 

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Discussion Starter #19
Went to the range for a little more testing

Brought the 94/mp5 with the Bill Springfield built trigger pack.
And my C93 with the special weapons trigger pack.
All I swapped out were the 5.56 ejector lever and the 9mm ejector lever into the appropriate trigger group.
30 rnds in 2 9mm mags
First magazine.....no problems
2nd magazine.......no problems
30 more as fast as I could pull the trigger.....no problems
Now for the C93
20 rnds in the magazine.
5 shots than a light click.....Hmmm!
Could see the bolt was a little short of battery.
Pulled the cocking handle back and took a look.
Wow ....WTF!!!
1 rnd stopped halfway in,the other couldn't see at first. It was smashed like an accordion.
That was it.
This pack is ****.
This gun has not done anything funny with over 2000 rnds through her.
Now it is doing crazy ****.
Never seen a FTF like this.
Will put the Springfield pack back on the 93 tomorrow to confirm she's OK.
Other than that the 94 is good to go !
Her steel sights were not to far off . About 4" to the right and 2" under @ 100 yards. Had to move the rear sight almost to the end of travel. That's some MKE's fault and some mine ,the cocking tube is not welded center and was hard to center the barrel perfect. I'll try to tweak it but I can live with it at 50 to 100 yards. I thought about using a bore sight laser next time.
Gonna shoot some more this weekend than over to a buddies to ceracote the 94. Ordered my finger print cards from ATF and will be putting my Form 1 for Sbr stamp in the mail as soon as I get printed.
 

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I'm glad you got it figured out as to where the problem is and how to fix it, even if you don't know the exact culprit.
Hard to say what the issue is. All I know is that sometimes these things feel like they have a spell or voodoo cast on them. I've fought mysterious problems like yours and others before and never figured out exactly what the issue was, just what fixed it. I mean, one ejector can look, feel, and operate in the hands exactly like the other but the damn thing won't work in the gun consistently. Same thing with extractors and springs. Can't see a difference, can't find a difference with a loupe or caliper but the damn part won't work.
I recently had a POF that wouldn't run consistently, multiple failures to eject. I looked, I checked, I dressed and cleaned and smoothed everything I knew to try and help it out but it would not run consistently. Got better, went from 6 to 8 failures per mag down to one or two but never ran perfectly.
Atlantic had me return it and they tested it. Ran perfectly for three mags. WTF? Matt said he'd test it again the next day. He did and it finally gave him some trouble. Moody gun or what??
Atlantic sent a replacement and but for one hiccup at the end of the second mag it ran perfectly and still runs perfectly. I look at the trigger pack, ejector, extractor, bolt head, everything looks and feels exactly like the one I returned with one exception, the new gun feels smoother than the last. Go figure. I could tell stories about an SW5 I had years ago and the very first G3 I ever owned but I digress.
Toss that cursed pack to the wolves and pick up a new semi pack from HKparts and never look back.

One last detail about my POF. The serial number I received as a replacement for the original number was consecutive to the one it replaced. One digit lower. Thought that was cool and odd at the same time. Brothers on the line, most likely put together by the same guy but one won't work.
The form 1 on the new one goes out this week.
 
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