For those who don't wish to follow links, I basically paraphrased the EGW article, a snippet of which is presented here:
"The phenomenon of mounting a dot to guns has exploded within the past few years. Originally an aftermarket customization, more and more manufacturers are now making their firearms optics ready from the factory. There are still tons of guns on the market that are not red dot ready though. We understand it can be cost prohibitive to modify a slide. A few hundred dollars for the modification added to the (potentially) hundreds of dollars in optics. At that point, you are stuck with the mounting footprint that you chose, so if the industry evolves (which it NEVER *sarcasm* does) you better hope they choose to move forward and innovate based on the footprint you had milled into your slide.
Speaking of footprints, there are 4 major footprints used to mount the red dots and it feels like every manufacturer seemed to have used a different one just to spite you and us. Some even go so far as to use different and proprietary footprints on similar models of guns, thus confusing the end user even further (you know who you are, Sig Sauer)."
