Ruger Loader

This is a slight upgrade to most loader options I've seen. I designed this with a pin that slots through the round hole near the bottom of the mag to hold the spring down. The pin has tight tolerances and can be stored inside the loader body. I've never had mine fall out in my gear bag. Because of those tight tolerances, however, I don't recommend inserting it all the way while it's in the mag. You will likely need something to pop it out because it sits flush with the body. I added a small grove in hopes that a fingernail would be enough to pull it out, which it was when I first printed the part. But after a year, it seems like the PLA has swelled ever so slightly and it's no longer easy to remove if seated fully with the pressure from the mag spring. The images show the length it can be inserted to lock the spring down while having enough room to grab it with your finger. 

This 100% needs supports inside the hole the pin goes through. The other overhangs should be shallow enough that they don't.