I can speak to what they have been used for to the present. One is that there are individuals in Canada who travel to Africa to hunt big game animals who have their own rifle. They prefer to take their own rifle with them, so they own a rifle in Canada that is not routinely used for hunting in Canada but is the firearm they would take with them when they go somewhere else to hunt a game animal that requires that level of energy.
The second broad use that occurs at present is very long-range hunting or target shooting. These are circumstances where there's an attempt to harvest game or hit a particular target at distances of a kilometre or more.