I just installed this safety in my Commander about a week ago. I have heard from some that the safety was a drop-in (perhaps for the full-size 1911), but that was not my experience. Here's a full account: The safety that Ruger supplies is manufactured by Novaks. I'm not sure what the terminology is, but the safety has a small notched cylinder that has to fit to the sear. The shape of this cylinder and notch is slightly different on the Novaks than it is on the factory safety. The factory safety is flattened along the top. I filed and polished the Novaks to match this. This allowed the safety to slide in all the way; but it would not move to engage. At this point I carefully filed the side of the notch that is adjacent to the flattened side with a bevel, matching it as closely as possible to the shape on the factory safety. Because of the curve, I found this very difficult to do. It took several test-fits, but eventually the safety seemed to move. To be truthful, I was starting to re-assemble the gun, when I realized that the safety movement just didn't feel right. I noticed that it wasn't moving quite as far as I thought it should. It was functioning, but it seemed to stop short. I put the factory safety back in, and found that the uppermost point of the safety traveled to a point adjacent to the top of the groove that the slide rides in. The uppermost point on the Novaks is truncated, but it was clearly not traveling nearly as far; closer to the bottom of the groove. I deepened the bevel, test fitting several more times, and got the right travel. As a temporary measure, I applied paint to the metal for a little protection. For more permanent corrosion resistance I plan to apply blue, since this area isn't visible and I'm not sure that it merits figuring out how to apply the black oxide coating, if that's even doable by an amateur.
Just as a note, this was my first attempt at DIY gunsmithing, and on a brand-new, never-fired 1911, no less. I did the full 1911 safety check afterward (and before just as a benchmark), and it passed with flying colors. I've fired about 250 rounds through it, and had 2 misfeeds (PD ammo after the 200 mark), but otherwise no issues. I've done a little more work to resolve the misfeeds, but haven't had a chance to test the result yet.
