I thought you just had a brass nock or something, not a string loop. Whoever did your string loop did it wrong. If your loop is that loose I would suggest not shooting your bow until it is fixed. You may be running the risk of it letting loose on you. You could smack yourself in the face and or launch an arrow into oblivion when this happens.

Not too mention if the loop moves freely up and down your string how could your nocking point be right, or consistant?

Maybe I am confused as to how it is done? Is it just a loop on your string, and the arrow nock fits between the two knots? Or is there a brass or tied on nock above the arrow, and a loop under it? This isn't very comon, but some do it. Either way it shouldn't really be loose.

What is keeping your nocking point the same from shot to shot is what I am asking.

A string loop is normally tied on so it is tight on your serving, you can't just slide it up and down. You can however turn it up and down the serving to adjust the nocking point. Sort of like threads on a screw. And the way the knots are tied every time you draw the bow it tightens them, so they should always be tight. And they should be tight enough that it will align your peep. If you are using a loop you should not have to have the rubber peep aligner. You can adjust the loop and the peep so it will align right without it.

Would it be possible for you to post a pic of your set up for us? The picture I have in my head is not good, but I may be confused or something.

Paul