It is very water soluble, I used to be able to get the contents from 4 to 5 OC80's in 3ml of water.
Best way to shoot those pills is to first filter it with cotton, the micron filter. After removing the coating, I would crush, mix with the desired amount of hot/warm water. Then, using a 5ml syringe, Id take the plunger out and stuff a smallish amount of cotton into it (maybe just enough to ip to .5ml mark), and pour the oxycodone pill slurry into the back of the open syringe. I would then put the plunger in and force the slurry into the cotton, and collect the filtered oxycodone into a clean shot glass. Finally, I'd filter that solution with a micron filter.
Shooting pills is never safe but this is the best approach if you're going to go about it.