Another worthwhile note..
Depending what hopper your using, instead of sanding it down, you might want to put a little gun grease on the hopper neck before sticking it in the Ion Feedneck, (For example, when i first stuck my Egg in it, i broke the egg trying to get it back out, after replacing the egg neck, i fing just a smidge of grease inside the feedneck still gives a rock steady hold while making it "twistable" to get it off without breaking your hopper...
im also sure i remember some dude here taking a dremmel to it because his hopper jammed in an ion.