That's strange how you managed to get a Canada only form of HM in the US. Because IR Oxy stops at 20mg here, I assume you mean 30mg roxicodone and not 30mg oxyneo/30mg generic oxycontin.
Hydromorphone is very weak when eaten. If you can handle 30mg of oxycodone, you can eat the whole HMC 30mg. Even with little tolerance eating the 12mg and 18mg ones did very little, but eating a 24 once I felt what it was to have a 12 hour hydromorphone high, it's pretty great. But not grounding the beads of the HMC 30 in a mortar is making me cry, so many shots or snorts in there. But if you don't feel safe eating the largest dose possible of HydromorphContin, I say just remove a little beads from the fat red capsule. But I would just eat the whole thing and have some benadryl handy in case you feel nauseous. 30mg oxycodone, which although you did not mention if it was IR or oxycontin or generic oxycontin, I'll assume you're american and taking 30mg IR oxycodone pills, is stronger than 30mg of hydromorphone, when taken orally...so, take it from there. I really recommend giving the grounded beads powder a snort or two, very small lines, until you hit a sweet spot.