The threshold dose for my cat (she has a large opiate
/opioid tolerance) will of course vary with opium
because opium has an unpredictable morphine
content. The active in opium is morphine. My cat smokes multiple grams of raw O in a session so for someone who doesn't do much opiates
/opioids, a ball the size of a large pea as a good place to start with raw opium. Cooked flake opium is a lot stronger because it is refined for smoking so the dose for that would be a match head sized piece.
In the end, with experience you can determine how many mgs of morphine you are taking approximately. Sorry if this is kind of vague or if it goes off topic btw, my cat, in whom is informing me, is very relieved of pain due to the smoking of massive amounts of raw opium along with the rectal and oral administration of concentrated poppy
The dose of oxycodone
is similar to morphine so. Start low work your way up, with smoking it is more of a smoke it til you feel good to stop kind of thing due to the quick onset. It can take only minutes or less sometimes to feel the effects.
Smoking would be more akin to banging (IV) morphine or oxycodone than eating because of the rush and quick onset but smoking also lasts far less time from 15m-6h depending on how much was smoked and how long one spends smoking it.
Use the search engine next time, mate. Hope this has helped.