The grandson works at one of the Mayo Clinic hospitals in town as a surgical supplies technician. He's actually in charge of a whole department and gets not only new equipment in to put in inventory but also gets stuff that's headed for the scrap bin. These three syringes came to him today as discard. The smart thinking laddie just brought them by thinking they might be handy for the plastics stuff.
All three of these have tolerances so tight that there are no O-rings on the plungers or barrels. What they were used for in surgical application was to inject liposuctioned fat in other places on a body to sculpt it. They've all been run thru the sterilization process and are squeaky clean. I'm going to try the smaller one on an open pour mold where some smaller pieces need to be filled to see how well it works. If it handles the plastic ok and if the plastic isn't a bear to clean out of the barrel after use I'll probably offer the other two in the classifieds. I don't see how they wouldn't work for that sort of plastic work, but time will tell.
I think they'd work well for injecting brine in something before smoking too. Always some new play thing, eh. The barrel sizes are 3, 4, and 5 inches.