I just got a M6a2 stretch upper to go on my IC lower. I know that the Samson rail fits the older M6a2 with the regular barrel nut. However I have the newer square style barrel nut. I also know you have to cut away a bit of the thermal sleeves to fit the square barrel nuts. I was wondering if the Samson rail would make contact with the stretch gas block and whether or not i'd have to grind away for clearance. Does anybody run a samson with their stretch upper?

I put the samson evo 15 on mine.  Worked like a champ.  Here's a link to a video I did. https://www.youtube.com/watch?v=rRhBYWTbi6Q

The newer m6a2's have a different barrel but and gas block. I'm not sure about the stretch, but I'd assume its a different gas block than the older a2's. The new barrel but is not a problem, however the gas block is. Guns with the new barrel but but older gas would work with the Samson rail. My m6a2 has both, and I don't think you could remove enough material to clear the gas block. I don't know for sure, but it seemed to me it would take a lot. This was also the rainier arms evolution keymod, which should have identical dimensions to all other evolution variants. I'm still debating on returning mine, keeping it for another ar, or modding it to fit(not likely). Let us know what you find I'd like to know if you got it to fit.