We used Piliguard pinkeye vaccine about a month ago - and yes the syringes did stick. I tend to think the main problem was the consistency of the stuff, and the fact that the dose was only 2mLs. Best solution I see is just to have plenty of extra syringes. I think I picked up a new one about every 10 head.
As far as sticky and non sticky vaccines...seems to me the Ultrabac 8 was average, but the 8 way Schering makes was by far one of the easiest I've ever done. I don't recall ever having to replace the syringes for the ~60 head we vaccinated. Virashield is average to sticky, Breedbac 10 was average, Bovishield Gold was average.
For some reason it seems a lot of those drugs that are WHITE - like Penn, Excenel, etc are thicker and make those syringes sticky a lot quicker than normal. Most of the clear ones are fine, like Banamine, but then again, Nuflor is pretty thick. LOL.