That's the shank of the barrel and it's supposed to be like that. Check all 4 of your screws, one may be one that's shorter than the other three - that's the one that goes in the front hole. If they're all the same length, you might have to shorten it yourself. (sometimes the base manufacturer will just machine the hole in the base shallower so they can use the same length screws in all 4 holes)
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