Hopefully my 300 win will be here next week. I'm interested to see how the stock fits and the scope mounts if those bases put the scope up high maybe that's how the m16 ejection angle works. My challenge with those type of extractors is that I like to mount my scope as low as possible and many of my scopes are large.
I understand your concerns. I do not use scopes with large windage turrets (only capped) but I like my scopes mounted very low as well.
Over the last couple years I have had to sell a three rifles with M16 style extractors that I really liked, because I just couldn't find a scope that worked at a mounting height that was acceptable to me due to the high angle of ejection. I understand the extractor can be "tuned" to result in a lower ejection angle, but I wasn't ready to trust that, and being a cost/benefit kind of guy I felt it was better to just move them along.
Now, I am always a little concerned about buying a rifle with an M16 style extractor.
It appears that the bases included on the M21 are much thicker than a Warne base (for example) so maybe that is a way of eliminating the issues for most buyers. But hat really wouldn't satisfy a low-mounted scope lover.
I really like the rifle, and I'll be anxious to hear how it works out for you. I hope it works out well.