Though some are timid to admit it, I am amongst the experimental types and I always found 'liquid suppository' superior to smoking in terms of getting the most out of it if you're not wanting to inject.
I don't have the bioavailability on hand (having only a phone right now and being very busy with work and DOC limits my assistance and the footwork I am normally glad to do, esp. as a moderator)
As for a heads up if one chooses to do it in this way: oral syringes are rather large but I never had much difficulty in removing the hypodermic needle in whole. A lot of times I'd even use your basic pair of scissors and work the tapered part of the plastic tip off with a light sawing motion.
Then break it down in a half CC (give or take) and once it's a solution (I was using tar so it takes a second if you back-load, but you could even prep it in a spoon first, removing the needle-head correctly shouldn't interfere with drawing, but you could do this prior) administer it laying on your right side, a bit toward the prone position.
Note especially that after pressing the plunger down entirely, you should rapidly take the plunger out completely *without* the rest of the syringe barrel, leaving the base still inside; this prevents suction leakage. A moment or two later you can remove the barrel by the grip. Wait a couple of seconds to a minute later and voilà, you should get an onset, perhaps while still waiting, and depending on chronic tolerance, even a bit of a rush. The works get a bit messy, but I'd keep them cleaned and reuse. This was on occasion when I wasn't as experienced or was uncertain about my tolerance and the quality of what I was getting