I notice no one has pointed out that the BA of plugging vs oral vs intrasal vs IV is quite similar with oxycodone?
Of course IV will be the highest, but the difference between oral, intranasal and rectal use of oxycodone is more similar than different. The substantiative subjective difference of effects between any of these ROAs will be the "rush" or time of onset.
Given the potential risks involved in IV use, particularly injecting pills, I don't see a worthwhile benefit either in BA or half-life when it comes to injection versus other safer ROAs.
Anecdotally, I always found oral oxycodone use to be the most long lasting, followed by IV/IM/rectal followed by intranasal.
Why not try potentiating your oxycodone with something like diphenhydramine/promethazine and/or Tagamet/cimetidine before you try some other more dangerous form of use? I'd take oral oxycodone use combined with cimetidine and diphenhydramine over intranasal use or even rectal use or injection use any day (for the aforementioned reasons).