I finished my Polymer80 PF940CL build and was pretty happy with the results. This is a really interesting Glock-compatible variant that is unique to Polymer80 that I really like. It’s a G19 lower designed to work with a G17 upper. This is why they call it the “compact long” (CL) model. Basically the handle doesn’t print as much under clothes plus you have the longer barrel and slide with the longer sight radius. It’s a win-win.
The Slide Sticking/Catching Open vs. Locking Open
Due to a function problem on the PF940CL, I realized that I needed to come back and update this post. If your slide gets caught open part way then this blog post is relevant – the recoil spring is getting caught.
On the other hand, if your slide is actually locking open and then slide lock lever is engaging the slide when it should not be, then you need to assess the lever specifically – click here for a new post I wrote about that.
Fixing the Slide Sticking Open
Back to the story, I built the PF940CL and it function tested just fine. It shot like a dream other than the slide sticking, or catching, open once in a while. I had a pretty good idea the recoil spring was catching on my purposefully so-so sanded area where I removed the barrel block from in the frame.
I bet you’re wondering – wait – what? He did it in purpose? Yes, I did. I’ve read about guys having this problem and wanted to recreate it for a blog post and also to allow me to demonstrate a new sanding tool kit I’ve assembled to make the work easier and faster.
To avoid this, just be real careful about not leaving an edge. Historically, I would mill out most of the plastic and file the rest down flat using a combination of wood dowels and popsicle sticks to provide a stiff backing for different grits of sand paper. It was tedious but it got the job done and it will work for you as well.
A better way…
Ever since my first Polymer80, I was wondering how I could reach in there with a hand tool and get ridge of the plastic in a more automated fashion but also still have enough control to not make a mess. For example, a die grinder with a burr would scream through the plastic and destroy everything in the blink of an eye,
Dremels / rotary tools give you a ton of sanding options but nothing that would allow you to reach straight back from the nose of the frame and be able to sand the “U” and its curved surfaces.
I kept digging around and hit on the idea of using a 4″ shank mounted in a slow turning hand drill and using sanding rolls. That worked great! I was able to source 80, 120, 180 and 240 grit rolls to allow me to start course and move finer and finer.
So the sanding kit includes the You don’t need it to be so smooth that it looks like it was never sanded – that’s why the sanding kit only goes up to 240 grit.
Start with a lower grit and move up to the 240 grit. The 180 and 240 grit drums will clog up with plastic pretty quick so they are more for finish sanding than removing a lot of material. I use compressed air to blow the plastic out of the drums and you could do that or use a stiff brush to clear the drums as well.
|Please let me stress to you that slower is better. If you are using a drill on high speed or chuck these into a die grinder, they will remove material super fast. In my honest opinion, too fast. I have my old Ryobi drill on it’s low first gear speed and just take my time by sanding a bit and checking over and over. I would urge you to do the same – you want to remove all material inside the “U” but no more.|
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