You can achive the same result by using the end of a disgorger and a needle (the type that you use to undo wind knots in line)
Tie your loop loosely, then slip the loop over the end of the disgorger and then put the needle into the centre of the overhand knot.
Holding the needle you slide the knot as it tightens all the way down to the disgorger, and hey presto, you have consistent sized loops everytime.
(and you have saved a couple of pounds on the loop tier ;-o)