N.J. Phillips 25ml o-rings (5 pack)

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O-rings are the first thing to go on any piston applicator and the last thing anyone thinks about. They sit on the piston and seal against the cylinder wall, and when they harden, swell or nick, the gun stops drawing a clean charge. What you see is a dose that comes up short, dribbles from the nozzle, or takes two pulls to fill. What you do not see is that every animal in the run got less than the gun says. This is a five pack for the 25ml applicator. Buying them five at a time is the right idea, because the failure always happens in the middle of a job and never in the middle of a quiet week. Fit is the whole game with these. A worn ring slips and a wrong one binds, so use the ring made for the barrel it is going in. Lubricate on assembly as the manufacturer directs, rather than forcing a dry ring into a dry cylinder, which is how you tear a new one on the first stroke. Check dose accuracy against a graduated cylinder after any rebuild, and rinse the applicator through at the end of every session so the rings are not sitting in residue overnight.