SilverBlueMedallion
chuckebaby
Make a "Split" using the Split tool (Or keyboard shortcut "S") to split the clip right where you want to stop.
You will be left with a small clip, 1 or 2 beats long. then proceed to Craig's suggestion.
You'll be good to go 
There's no real "Fast way to do all this in the Step sequencer. Your better off converting it to midi, groove clip looping to utilize groove looping and dragging.
yes but then i an still stuck looping the rest of the notes which i dont want to!
my kick, snare, percussive elements change as the 16 steps go.
you are only looping up until what you need correct ? you loop up until 16. then stop and build a boat if need be.
If are talking about only looping some of the notes (and not all of them ?)
you are in a total different ballgame and need to use Midi to copy partial kit pieces.
It can be done and I do it all the time, but not in the SS I don't.
I do it in the Piano roll view.
It may be possible in SS but I think you would find it easier in PRV.
That's about all have.
Best