My understanding is that crushing the MP tabs is not a problem as long as they are kept in the original packaging until right before they are used so that they are not exposed to light or air. I crushed mine very carefully so as to maintain the integrity of the packaging.

I had another sparklite around here somewhere but can't seem to find it now to compare. It's been a while but IIRC I shortened it about 0.25". I tapered it slightly also. I actually busted two others in the process of my shortening experiment. If you shorten too much the stopper, spring and all the flints fly 20' across the room on you. <img src="/images/graemlins/grin.gif" alt="" /> It's much eaier to do with the orange one though because IIRC you can shine a bright light through them to see the insides and know exactly how far you can go before you get in to trouble.