I found this inert shell decades ago at a garage sale in New Brunswick, Canada and finally got around to cleaning it up. I'm not really well versed in the various marks on it, but I've attached some pictures with the hope that someone on the forum could provide us with some information on it.
It weighs 27.6 lbs and I think it might be WWI era. It is 13.25 inches tall and 4.5 inches in diameter. It also has stamped on the body SF4765U and above the U there is an arrow pointing up. Lower on the shell there is an STS under the T there is a line and then a W. A little lower there is CN. On the bottom it has stamped on it S.E. CO 17.6.18 and above it is 45 HR IX or TX and then NO. Any help would be much appreciated. I can provide more pics if necessary