The graber clips are probably made out of copper or some copper alloy. After some time they seem to build up an oxide layer, increasing the contact resistance. When connecting directly together, the sharp edges pierce that layer and form a rather goot contact. But if you connect them to a round wire, the pressure gets distributed evenly keeping the layer intact. You need to rotate them several times to scrape the oxide layer away. That will decrease the resistance considerably. My experience with those clips aren't good, therefore I replaced them with alligator clips for low resistance measurements. Their sharp teeth easily penetrate any oxide layer making a much better contact.
Without measuring the inductance of the secondary, it is impossible to say if the turns ratio is correct. If you don't have a function generator, you can use the ESR meter circuit and connect the transformer and measure the output voltage. If the output voltage is about +/-200mV, the turns ratio is ok. You can use the other transformer as a reference for the turns ratio.