Thursday, April 21, 2022 It's not uncommon for folks to go into the task of replacing sights on their 1911 pistol with assumptions made from past experience of changing sights on their Glock, SIG, Beretta, S&W or other pistol and thinking that those experiences will carry over to a 1911 without further complications. Actually, there is very little that carries over. First, let's recognize that there are usually two different sight cut principles involved - the simple sight cut having a dovetail with a floor and two angled sides (like, say a Glock) and a complex sight cut having a dovetail like the simple sight cut, but with flat horizontal surfaces adjacent to the dovetail, before and/or behind the dovetail, as well as multiple level horizontal surfaces connected by angles, radiuses or vertical cuts (like, say a Springfield Range Officer). So the first sight replacement experience someone might have, might be with one of those pistols named above having a simple sight cut. Bear in mind that there are very few of the aforementioned brands like Glock, Sig, etc, slides are made by anyone other than the original manufacturer (although Glock and SIG are starting to be the exception here) and because there is only a slide manufacturer involved, they manage to cut that simple sight cut with pretty good consistency. Some of them add a little feature at each end of the dovetail cut to widen the mouth of the dovetail making it easy to start a new sight into the dovetail. Another thing that sight makers build into their products is a "crush pocket" in the bottom of the sight's dovetail. These two things allow you easily start a new sight into the dovetail and then as you crank on the sight pusher, the bottom of the sight can collapse as it's muscled into the dovetail. Rarely does the installer have to measure anything or pick up a file. The sights are often only held tightly by the center third of the dovetail. Not really a bad system for a mass-market gun, so long as you stick with the simple sight cut principle. In the 1911 world there are dozens of companies world-wide making these pistols. Adherence to dimensional tolerances in sight cuts from one to the next is sad, as there are no industry standards in force. This is compounded by the fact that they are cutting their slides to mount one of a large variety of sights made by many different sight manufacturers, again who aren't held to dimensional standards, other than what it takes to get their low bidder, import sight mounted on the 1911 manufacturer's slide. So long as the slide maker and the sight maker come to an agreement, they typically care little about their product fitting any other companies’ sight or slide. Some of these import, low-bidder sight makers care little about how their sight fits a sight cut, so long as it doesn't fall off. It doesn't matter if you can slip a business card between the sight and slide. So, when you as a aftermarket sight manufacturer recognize how much tolerances can vary, you realize that you have to make your sight with dovetails sized slightly oversized. You can always file material OFF, but you can’t file material ON! Another consideration is how nicely you want the replacement sight to fit to your slide. This means that the dovetail has no gaps other than small corner chamfers and the flats of the bottom of the sight sit tight against the slide with the minimum light gap possible. Fitting a 1911 sight requires a careful installer having the skills and tools to measure dovetail widths and depths accurately on both slide and sights, calculate how much material needs to be removed from the dovetail on the replacement sight and accurately file the excess material from the right places. Additional measuring, filing, test fitting and inspection as the sight starts to fit into the sight cut will need to be done. Constant checking for interference must be done as the fit comes closer and those spots where hard contact appear must be clearanced, even outside of the dovetail on other places on the underside of the sight. Also, the installer needs to be able to work with the new sight without scratching or mauling the outside finish, or the sight will have to be reblued when the fitting is complete. I’m not writing this to discourage you from installing a new sight on your 1911, just to inform you that there’s more to it than shoving a new sight onto your S&W M&P using a sight pusher. If you need help with having a professional installation done for your rear sight, fitting and installation services are available from Harrison Design, starting at $55, if you send us your slide with the old sights still installed.