I don't know about the crushing. A couple of years ago I ran a .45 Auto case into one of my .44 Mag dies by mistake. The result was just a new bottleneck wildcat. The brass went in and out just fine, though. So that simply depends on the radius of the mouth of the sizing die. What should be noted, though, is that the case will get longer when you narrow it, so evaluation of the trim length should be done only after sizing. At that point my .45 Auto case would not have failed a case gauge check.
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