Try kratom or even tramadol first. They are in the same league as codeine but have different mechanisms of action.
If you try tramadol dont go above 300mg, especially if you are not using benzodiazepines (stay off benzos for recreation!!!), due to tramadols propensity to cause seizure at 400mg+ level doses. Some people metabolize tramadol into O-desmethyl-tramadol better then others and they are those people who really like tramadol. O-desmethyl-tramadol is metabolite which is actually most potent mu-opioid agonist that tramadol has to offer. Beside that, tramadol is also a serotonin–norepinephrine reuptake inhibitor (SNRI), with imidiate effect. Be cautius for interactions. Tramadol is a weird drug, people love it or hate it. I guess it depends on how good is your body in converting from parent drug to O-desmethyl-tramadol metabolite.
Other opioid I would strongly suggest, before going up in the opioid hierarchy is KRATOM. If you live in USA than it is legal and even if you are not from states there is a high probability that kratom is legal in your country. Before ordering check the legal status. I say ordering because you don't want kratom from head shops but from some reputable vendor. There are many great vendors out there. To talk about strains, special mixtures, tinctures and other things would take me ages. Use the search engine to find about it. I will say that my 3 favorite strains were "Green Malay", "Red Bali" (actually Red Borneo but it is called Bali) and "Red Thai Maeng Da".
Kratom is a plant with complex pharmacology, but is similar to tramadol in that it is also SN(D?)RI. Kratom effects multiple opioid receptors (mu, kappa, delta), serotonin, norepinephrine, dopamine and is NMDA receptor antagonists. It does all that and who knows what else. Research of kratom is disgrace to such complex plant. But it is a plant so there is one big reason why very few are interested.
With the right strain (mix) and appropriate dosage kratom can get you feel similar to 10mg oxycodone. That is at least my experience with this very useful opioid. Having said that, kratom is partial agonist of mu opioid receptor and you can not expect effects you would get from high dose of strong opioids like oxycodone or morphine. If you go into kratom extracts that can change but then you are at the level of strong opioids and price you pay is high financially and also psychologically. Stay away from extracts and kratom will be more than enough.
You don't have to go directly to oxycodone/hydrocodone/morphine, so kratom is what I consider logical next step if you insist to go deeper into opioid world. I am not your mother but I have to say that you are playing with fire. If you are not very stable person opioids will control you eventually. THERE ARE people who can control their intake and do even heroin once or twice a month. Maybe, as some statistics are showing, this stable recreational opioid users are majority, I would not be surprised. BUT if you suffer from depression or anxiety disorder then you have found your cure that will become your curse when your tolerance inevitably goes up.
I will assume that you are stable person that can control their intake of opioids. In that case don't make the mistake off skipping grades and go directly to oxycodone from codeine. Kratom has lot to offer if you treat it with respect it truly deserves. It is a world of its own with different types (think in terms "hydro-krat, "oxy-krat", "morph-krat"...) and high dosage variability.
Tramadol is an option, but kratom is just much better one. It is overall safer, legal to buy, much more diverse and better IME and withdrawal is easier to handle than withdrawal from tramadol.
Stay safe. Peace.
Soma
