I recently did this with the Gel-Type MS Contin 30s; I can thin the gel out enough to put through a 29g, and make the solution so it just doesn't leave one glob.
Even with the modified thinned solution, it is quite viscous and you have to use a little more pump strength to inject it, but really it isn't really worth it much.
Because it is a thicker liquid/gel, it "sticks" to the tunnel of your vein and intensifies the damn Histamine reaction 10x sometimes; my wrist (from my hand to halfway up) looked like one big mossie bite 2/4 inch above my skin, and the induced edema in my left and right hand took over 3 days to subside (my hand looked like a baseball), and this happened on several goes and several spots, every drop IV, and it gets worse the thinner the vein you use also.
Also like to add; 1 Drop went IM on the top of my hand, it did not swell, but it left a ball of gel in that spot you could move around a bit for around 5 days after, it was kinda weird in the good and bad way.
All in all, the Morphine