Since Kalashinkov USA introduced the KP-9, I’ve had a handful of guys ask me to make a quick takedown pin for it. Well, it turns out it is a unique size and the hinge pin would need to be around 3.75mm – smaller than what any of my vendors could reliably hit. My existing pins all have a diameter of .156″ or about 3.96mm so they would not work.
So, what to do? I’d bought a KP-9 with their brace and it was a nice weapon in terms of fit, finish, and operation. I’d pressed out the unique hinge pin and saved it so I could have replaced it but I decided to go another route. By the way, the original pin was swollen at the ends from being set but the middle measure 3.75 so that’s the number I was going with.
How To Remove The Original Pin
I used a punch on my air hammer to pop the old pin out. You could also press it out or drill it out.
Reaming the Hinge Hole
If you look at the hinge, there is enough material around the hinge pin material to ream it out a bit. I decided to get a 0.1563″ (3.97mm) cobalt reamer and a 4mm cobalt reamer. My thinking was to first try the smaller reamer and if that proved to be too small, I’d step up to the 4mm (0.1575″). I bought mine from McMaster-Carr but you can get them from any reputable vendor.
Reamers are cool – they make perfectly round holes and you can do them in a hand drill if you are so inclined, which I was. Secure your weapon in a vise so it can’t move, use a drill bit or other pin to align the hinge parts from the other direction. As you ream, this slave pin, or alignment pin, will be pushed out of the way as a reamer’s head is blunt.
Put your reamer in your drill chuck and coat it with cutting oil, then slowly insert the reamer into hole – let it cut – don’t force it. You’re not taking off a ton of material so I reamed the hole out in one go.
The slave pin did it’s job and I had a true hole in the end. Okay, the .1563″ reamer’s hole worked but was too tight – If you don’t intend to pul the pin much, it would work but it was not what I wanted. I then did the same thing by inserting a slave pin but this time used the 4mm reamer and it worked great.
You see, getting the hole size right matters a great deal compared to some weapons such as the M92 and Krinks – they want to cam the cover up so there is tension that locks everything in place. With the KP-9, the fit of the dustcover relative to the rear sight block is so good that there isn’t tension so you need the quick takedown pin to fit snugly and the detent ball to do its job.
I really like how it turned out. For folks who want to add a quick takedown pin, just order the AK-V pin [click here to open that page in a new tab] and then ream your hinge open. Note, you might want to get the same size reamers and see which you prefer – start with the smaller one first of course.
Note, I have to buy all of my parts – nothing here was paid for by sponsors, etc. I do make a small amount if you click on an ad and buy something but that is it. You’re getting my real opinion on stuff.