Oxycodone is widely considered to be the pharmacuetical opiate legally available in Oz which is "2nd-closest" to the heroin experience (both by users and by the medical fraternity). Hydromorphone, aka Dilaudid is considered the closest; but it is almost never released on prescription, but rather reserved for pain relief in hospital settings.
Having used all three, and a dozen other opiate pharmies besides, I would agree with those comparisons. As such, experiences of smack and acid are probably useful measuring sticks.
When I was tripping several times a week during my late teens, shooting other drugs shortly after a trip peaked was one of my favourite experiences; I have cocktailed heroin and LSD in this way many times. Later, when I had a sizeable hammer habit, basically everything I did was done while experiencing some degree of effects of heroin. Most texts I have read suggest that opiates "kill" acid. It is undoutebtedly true that heroin can tone down the intensity of the trip. But Oxy and hammer, at the right doage and given the right conditions, can have their own "trippy" quality: lucid dreaming, that wonderful "cotton-wool" haze etc. Benzos like Valium of Serepax do "kill" trips in the arse, but cocktailing the euphoric opiates can allow the creation of a distinctive experience.
The influence of the opiates on the trip (IME) varies a lot depending on the point at which the opiates are consumed.
At the time of my most frequent use of this cocktail I was dealing with a lot of mental shit (notably prognoses which gave me a couple of years to live.)
At times this shit would force the onset of a bad trip.
A useful analogy might be a room's lighting.
Injection of hammer shortly following peak generally resulted in a fairly self-contained and introspective Mibrane, but invariably one with a smile on his face. In bad trip mode my mind was like a fucken fluro-filled 7-11, casting harsh brightness into every corner of my psyche, hurting my Third Eye, and making me see things that I didn't want to see 8( . Heroin not only turned on a dimmer switch, it replaced the entire scheme with 15-watt bulbs with tasteful shades, and lava-lamps. My psyche was still lit, but I could shadow over the cockroaches scurrying under the shelves. More to the point, I could highlight the best areas; not harshly, but in colorful, alive, and shifting tones.
In good trip mode it was a bit like replacing a strobe's driving intensity
with a sweet, but small, green laser %) . The tunnel focused attention inwards, but who doesn't love a laser?!?
Use of hammer prior to tripping basically meant the room was like a candle-lit restaurant- its not a massive trip, but the flickers, and shadows, and the uniqueness of every flame, allow for a friendly, connected experience
It seems you are likely to be swallowing the OCs and perhaps chewing through in order to outsmart the sustained release mechanism?
I hope this has, ahh, cast some light