taiden, thats exactly it.
If you're editing on computer, Audacity (freeware) has a zero crossing feature. just highlight your selection, hit ctrl+z and it automatically finds thezero crossings. It doesnt always find zero with the right sample lengths so you cant expect your loops to match BPM exactly.
Another way to fix the click of nonzero crossing selections might be to use the attack and decay settings(volume and/or filter) to hide the very start and the very end of the sample.
with or without the fundamental harmonics,