Yeah, some people have used one. X-dies have been available for some years and they haven't taken the market by storm; maybe there's a message in that? Thing is, they work okay for about as long as most cases will normally last before the necks split but even that small advantage mostly matters if we are excessivly setting the case shoulders back. PROPERLY done, normal FL sized cases will last just as long without much, if any, trimming. IMHO.