Sirex
Powered by natural gas
I am aware of the charging handle being extremely tight on some of these guns in the past and the first thing I do is check that for normal resistance. Have checked some in the past that were so tight that I was afraid of cutting my hand and/or breaking something on/in the gun and was unable to get the charging handle to the rear. Needless to say, those guns stayed up there. The guns we just picked up this month had the normal resistance from the first to last ones I checked, not once did I find an overly tight gun this time.
Are the ones you have new ones from Century?