1. Put your cigar into your Xi2 (or any Xikar guillotine cutter)
2. Line up where you want to cut
3. Close blades with just enough pressure to hold it (cigar) in place
4. With cigar hand apply slight inward pressure toward cutter
5. Swiftly cut your cigar
You shouldn't have a nub or bump or...well, you know what I mean.
Give it a shot a couple of times and see if that helps.