By default results are limited to 100, but you can change this in your code. This exists because (a) it helps performance and (b) in most cases more than 100 hits is not useful.
Well that makes sense, I do know the beagle-query --mime audio/mp3 command :-} But shouldn't it be possible to pass an argument to beagle allowing more then 100 - hacking the code for my own sake when this argument could be useful to others doesn't make any sense huh?