I've been thinking about getting a suppressor.

Here is what I currently understand:

1. Need to apply to BATF and pay the $200 "tax" for the can.
2. Need local LE to sign off on it.
3. If/When approved the same can can be used on multiple weapons of the same caliber.

Here is what I am interested in doing. I am thinking about getting a can for .223 cal and also being able to use it on a .22 cal and a .22 Mag. It is my understanding that the size and suppression ability of one for a .223/5.56 would be a bit of over-kill when fitted on a .22LR/.22 Mag., but that shouldn't be too much of a problem...right?

Am I missing anything?
If guns kill, then pencils cause spelling mistakes, cars cause people to drive drunk, cameras make child porn and spoons made Michael Moore fat. Human behavior is NOT caused by inanimate objects.