I tried searching but couldn't find anything on milling a slide to accept a red dot. Look at doing something like what the M&P Core has. I talked to a local gunsmith and he stated he has not done any S&W due to the fact that it may not have enough material on the slide.

Any feed back would be greatly appreciated

This isn't a red dot but the one for the M&P should fit and won't require any milling. Haven't heard too many reports about it but it looks interesting
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Norm

You might want to check out L&M Precision Gunworks, Galloway Precisionor Customized Creationz. They all mill slides for RMR mounts, not sure if they do it on the SD Series.