This got me to thinking about the bolt guns I have. Like 9Three, my '96 and '98 (9,3x57 and 9x57 respectively) both fully control the round out of the magazine. If by some chance a round gets ahead of the extractor, like just dropping one in the open action and trying to close the bolt, the claw will not snap over the seated rim.

In my CZ550 in 9,3x62, not a large round in the sense of a .404 or .505, the extractor claw does engage the round before it leaves the magazine, though not with as quite much of the claw as do the '96 and '98. The 550 will also fairly easily close on a 'tossed in' round pushed ahead of the bolt, snapping over the seated rim with just a bit of extra force on the bolt handle.