Not knowing the composition of the plunger does cause a problem, I have an old Winchester 350 and once a year I spray a little silcon mold release into the chamber and holding the trigger down I work the barrel back and forth a few times to spread it out, With the mold release once the vehicle evaporates you are left with something that will resemble case sizing lube, I am pretty sure that the plunger in my rifle is made of leather, and it is still the original, now I'm not saying positivley that this is good for your rifle, but silicon is pretty much inert so I doubt it would hurt it, I'm just relaying what works for me, and I'm not an expert........................steg