Could be the coke. I would use more water with that kind of an amount. I get gigantic rushes off of 0.05-0.08 let alone 0.1-0.2, I would only use an oral syringe for that. It's important to dissolve it completely and shoot it all at once. An oral syringe is the only way to go IMO, it's foolproof. As soon as you get in there, you're guaranteed to hit it. I never noticed a big difference with deep vs not that deep, lots of water vs little water, just having pooped or not, etc. To me, it always hits hard as long as I have more than 0.05 dissolved in 1mL-3mL and I feel it go in there. Tolerance plays a big role as well as quality, I bet your problem is the syringe is too big and deep and getting the solution so far and with such a small stream that it's going past the point of max absorption.