Go ahead and re-read my post; I listen to the full time professional gun machinists when they tell people what they're seeing over the course of hundreds if not thousands of optics installs. One if not both of them have stated they want any hs optic in hand for milling and install so they can be sure the cut is precise- because in their professional full time experiences the hs dimensions were not as consistent as expected.
Now, I didn't quote your previous post in my previous because I was being a gentleman, and stated what I'd been told without calling you out, you could've simply ignored my post or even repeated yourself without quoting me- but you chose to the negative path.
In the end, people should consult the full time professionals for best results.
OK, repeating someone you think is a professional is fine to a point, but I'm not sure you've fully processed the things you've repeated because they're somewhat contradictory. Hear me out; what I'm sharing is firsthand, not repeated from somewhere else. And while I don't know what you do professionally, I have a 20+ year career in mechanical engineering design (which is what this is) and testing, with a lot of practical machining experience on and off the job, so I am a professional with relevance to this as well. Don't assume the two people you've talked to are the only ones who know about this stuff, or that they're even necessarily correct.
We agree that the best results happen when you have the slide milled for your specific optic; that's what I've always preferred to do, and I wouldn't send a slide to someone who wasn't doing it that way.
But if you're sending the optic in with the slide, it doesn't much matter whether the optics have loose tolerances over the whole range of production, right? Maybe a little bit if/when you switch optics, but you can always have the slide adjusted to fit the next one if needed. Which, with the RMR the OP asked about, it won't be needed. The tolerances of an optic matter more when you're mass producing slide cuts to fit every optic out there, not so much when you're doing one-offs fit to a specific customer's optic. And those mass produced slide cuts are always looser than a correctly fit cut; they have to be - it's not because they're done better, it's because they want to avoid returns and rework.
Beyond that, due to the way the tolerances stack up, you can achieve a much closer & tighter fit by constraining the front/rear of the optic, than with the recoil lugs. The last slide I milled, for example, ended up at the perfect fit - once the milled surface was coated, the optic (a 507c) fit the pocket perfectly with light finger pressure, and didn't fall out when held upside down, without screws. That means the slide pocket itself transmits all the recoil, and the screws are just there to keep it from falling out. With a fit like that, the optic can be removed and replaced (to change a battery if it's an RMR, or other maintenance work) without needing to re-zero. But with that tight of a constraint, using recoil lugs as well is pretty much pointless - besides not being needed, there's very little margin between too loose to make contact and interfering with the fit; it can't really be constrained by both the pocket and the lugs. In contrast though, even a fairly snug fit with recoil bosses still allows some angular wiggle of the optic, enough that re-zeroing after optic removal is generally necessary.
Speaking as a machinist and an engineer, the recoil bosses aren't a better method or a requirement at all for the RMR. What they are is something for the CNC shops to point to and claim their product is better than what came before them - something all marketing people do, but that doesn't mean it's true.
I've had, or have, slides from some of the current bigger names like Jagerworks, Primary Machine, etc as well as Suarez and a handful of others including some cheap stuff too, but I've yet to find one with recoil bosses in it (again, for an RMR) that is as tight as a properly cut slides by some of the OGs of this kind of work like Mark Housel and some other now-forgotten names. My point to the OP here is this - don't select a shop because they've sold you on their recoil bosses being better, they aren't. Select the shop that promises a tight fit to the optic that you send in - one-offs, not mass production. Custom work is better in this, if your machinist cares about his work. (And to be clear, so nobody gets the wrong idea about my motives here - I'm not interested or willing to take on work for anyone here. I don't want any work, I'm just here to share info.)
And BTW Milf Dots, no, being the passive aggressive contrarian is not being a gentleman. If you've got something to say to someone, come out and say it to their face. That's why I quoted you. We can disagree and discuss it, and even agree to disagree at the end of the day without anyone needing to be offended or acting badly,
especially when we're talking about facts like this. Disagreement is not ungentlemanly, but pretending to get along while being passive aggressive is disdainful. JMHO.