I do get a plug at the end of the plunger and it gets plastisol past the O-ring also. I am using a infrared thermometer to get my temps. Dead on plastix says to get temp to at least 350 so that it cures correctly. It almost seems like the rubber isn’t out of the gooey stage. I wouldn’t see how though because I’ve shot baits at 380 degrees to see if that fixed the issue and still the same.