the length's fine. and by tapers you mean height, right, and not width? the height would just about disappear at the tangency at the muzzle. what i always thought was a very attractive rib. the width may narrow as well. only solid rib M12's i've had were 12 ga skeet guns. i don't recall their getting narrower but both tapered in height from even with the top of the receiver sighting plane to just slightly above the barrel OD at the muzzle.

roger