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Discussion Starter #1
I purchased a new Choate folding stock for my HK MP5K-N. The bottom hole is really tight when pushing the pin through it. Has anyone else experienced this same problem, and if so what did you do to correct the issue?

Thanks,

Sean
 

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I have the same issue. I was doing a test fit and couldn't get the pins in. I figured that I'd deal with it once my stamp gets here.
 

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Fitting an Hk marked Choate folder to SP5K with a sear installed required me to diamond file the bottom hole in the stock plate to even get the pins to line up. You want a tight fit, but remember that it will gradually shoot loose over time, so don't overdo it with the Dremel. Using a diamond file takes off very little material, and allows for occasional fitment to be sure you only take off just enough. Measure twice and file slowly, as my setup required an oblong shape to the lower pin hole for everything to line up cleanly. After the first 100 rnds, the top pin got substantially eaiser to insert and remove, and after another 300 rnds this morning, the bottom pin is getting easier, too.

My belief is that a combination of the back of the receiver getting flattened out to mate with the stock mount, along with slow battering of the pins as the bolt carrier hits the buffer results in gradually widening pin holes. My hope is that it eventually gets to the point that I can push both pins without needing a wooden dowel to remove the lower pin. Nice to have a solid lockup, however.
 

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Why don't you chuck a push pin in a drill and use fine sand paper and take a little off the pin.
 

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You know the push-pin itself can be the culprit. After time, the little wire retention tip can get bent out of shape and it makes the pin very hard to insert and remove. I had this same problem on my k-variant as well as other hosts. Try a new or another pin.
My general solution has been to go with the ambi pin on all of my hosts though you would still have to use at least one push-pin on the k. (The ambi's make it easier to move a sear pack around as well). For whatever reason, the hardest time I have with pins is on the K's.
Of course if the holes on the stock are actually mis-aligned, I guess that's another problem.
 

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Discussion Starter #9
Thank you gentlemen. I'll have to try to diamond file it. What bothers me is that I had another folder that was just as bad. It always bothers me to have to work on something like this that is brand new. You would expect it to just fit.

Sean
 

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I fit them in 3 steps:

** PERFORM ON THE STOCK, NOT THE GUN **

1) Stock off the gun, install a push pin across both sets of holes to make sure they are parallel and the pins themselves are not binding. If they do, use the same size drill bit (the size escapes me) and run it straight through the paired holes to square them up. Check for fit on gun.

2) Go one index size larger and drill the hole (on the stock) on the side that is binding. Test fit.

3) Repeat step#2 on other side.

4) If that does not work, I repeat step #2 and #3 with the next index size larger drill bit. I do not recall ever needing to go more than 2 sizes larger.
 

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Observation, but working on the pin was the first logical choice, but that pin would be seriously malformed to have worked, and then would only work in that one hole. In my case, that modified pin wouldnt fit in the oblong hole but in one orientation, either.

Filing on the pin holes in the stock ensures that you get a nice, firm fit to your specific gun. To restate, you'll need to study the lower where it intersects the receiver and then the stock to figure out precisely where to file. Just drilling out the stock fits that, but there are two other parts that need to fit as well.

To the guys doing this, just take your time and trial fit often. Would be best to stop once you have pin ALIGNMENT even if it takes a wooden dowel to drive the pin into place, as it will loosen up the more you shoot it.
 

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Discussion Starter #12
Thank Chopstix,

It just always bothers me to have to drill, sand and fit something that is brand new and made to work for a specific gun. I start to think that someone did something wrong during the making of the stock. What do I know, right?

Sean
 

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Thank Chopstix,

It just always bothers me to have to drill, sand and fit something that is brand new and made to work for a specific gun. I start to think that someone did something wrong during the making of the stock. What do I know, right?

Sean
The mold that use for casting the back plate is just a little bit off. I've grown accustomed to a simple rule of thought... if it's not made by HK, always expect to do some fitting.
 

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Thank Chopstix,

It just always bothers me to have to drill, sand and fit something that is brand new and made to work for a specific gun. I start to think that someone did something wrong during the making of the stock. What do I know, right?

Sean
I wouldn't sweat it. Think about the fitment between upper and lower receivers on AR-15s which are machined by the same company in the same facility. Even those have issues sometimes. Now consider you're putting something made in the U.S. by one company onto a gun made in Germany by a different company. Sanding the cheaper of the two components to make it fit is a non-issue.
 

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I have the same issue. I was doing a test fit with a friend's registered sear installed and couldn't get the pins in. I figured that I'd deal with it once my stamp gets here.
Glad to hear it. It's always good to follow the letter of the law, especially when posting about it on an Internet forum.
 

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I mostly did the chopstix method on my Z5p. All it took was a drill bit in there to polish it up a little (the stock holes, not the firearm), now they go in and out like butta.
 

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Discussion Starter #17
The mold that use for casting the back plate is just a little bit off. I've grown accustomed to a simple rule of thought... if it's not made by HK, always expect to do some fitting.
Fair enough, as long as my stuff isn't messed up. I'll try to diamond file it and see how it goes, referring to the stock and not the weapon.

Sean
 
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