Some hints for #2, 3, and 4.
#2 is a standard cartridge, and was once very popular among benchrest shooters, Walt Berger among them.
#3 is a very popular wildcat off of one of the most produced cartridges in America.
#4 is a necked down version of a cartridge that they actually changed the name of because the early guns chambered in this particular cartridge didn't have a fast enough twist for some of the ammo being shot in it and it shot poorly so they re-released it with a different name and in guns with the appropriate twist rate.