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Discussion Starter #1
I recently bought one of the SEF Navy style MP5K pdw pushpin lowers for my Z5P, and I can’t for the life of me get the thing to properly attach to the gun. The front push pin is no longer pushable for lack of a better term, and requires a mallet to get it in the hole. I can’t get the rear pin hole to line up with the one in the receiver, so I can’t attach my end plate.

My hope was to eventually sbr this and get close to an MP5K PDW as I could without buying an ambi pack, so I bought this trigger housing to at least get the lines correct. Seeing as how this was advertised as being “perfect for zenith or pof pushpin guns”, I figured it would be essentially a drop in component, but it’s not. Should I return it or are there any DIY things I could do to try to mate it up?
 

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Interference from the shelf welded to the back of the magazine well. At least that is what I found with mine. With all of the various HK housings I have had on mine, I have had to open up the front face of the housing to accommodate the shelf and it's weld on every one. YMMV.


-E-
 

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Discussion Starter #3
Interference from the shelf welded to the back of the magazine well. At least that is what I found with mine. With all of the various HK housings I have had on mine, I have had to open up the front face of the housing to accommodate the shelf and it's weld on every one. YMMV.


-E-
Thanks! Never done this before so I assume I can just dremel it out?
 

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It may be the shelf - I've heard of that happening on several occasions.

My pins were a problem as well, but not due to the shelf. In my case, it was simply a matter of tolerance stacking between the holes on the Navy trigger housing vs the holes in the receiver. I needed a mallet to drive them in and out as well. JUST A LITTLE reaming out of the pin holes in the trigger housing did the trick and now it's right as rain. It doesn't take much, so be careful not to overdo it. I used a drill bit (using it by hand as sort of a file), but a dremel, actual file, or something else might work fine.

Take a look and see if it's a hole issue or a shelf issue before you move forward with a fix. Don't want to "fix" the wrong thing.
 

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I would stay away from the dremel and stick to hand files.

I had the same issue about a couple of months ago. If you search my posts you’ll find the thread. From what I gathered, sometimes it’s as simple as opening the front face of the trigger housing as mentioned above. For me, I had to reem out the rear pin hole on the housing with the hand file. I would advise that you do not modify the actual receiver. That way you can always re-install the original factory trigger housing
 

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Thanks! Never done this before so I assume I can just dremel it out?
I used flat files on mine. File a little, test the fit. Repeat as needed. The opening on my housings ended up about 25%-30% larger to give me the swing down effect.

You have to remember that the semi auto shelf is technically "non spec". HK housings are not made to accommodate it so hand fitting may be required.

-E-
 

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Discussion Starter #7
Thanks again! I’ll give that a try.
It’s funny, I don’t get the swing down effect on the stock zenith lower either. I had a pof years ago that swung down and it was driving me nuts why this one wasn’t. I took my calipers out and would you believe it, the zenith one has almost the exact same size cut in the housing as the navy one that’s giving me problems. Go figure.
 

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I took my calipers out and would you believe it, the zenith one has almost the exact same size cut in the housing as the navy one that’s giving me problems. Go figure.
I guess it depends how much "almost" is, but that might be an indicator to double check the pin holes. Can you tell if the block on the mag well actually fits in the cut-out or not?

I only ask because I bought my Navy trigger group expecting to have this issue since I'd read about it happening, and it turned out the mag block fit just fine. There was no marring around the cut-out where it was bumping the edge, etc. I thought, "Well, f*ck. The block fits fine, but the housing still doesn't fit." Thus, I investigated the pin hole alignment.

For what it's worth, I don't know what kind of trigger housing group you have. Mine was HKParts brand, so I immediately suspected its specs. (Not that they don't provide good stuff, just saying it's a vastly different manufacturer than a HK contract/HK proper shop.)
 

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Thanks again! I’ll give that a try.
It’s funny, I don’t get the swing down effect on the stock zenith lower either. I had a pof years ago that swung down and it was driving me nuts why this one wasn’t. I took my calipers out and would you believe it, the zenith one has almost the exact same size cut in the housing as the navy one that’s giving me problems. Go figure.
Swing down MKE.

277495
 
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