Like Graybeard says, Browning made the LoWall in .243, as well as .223 and .22 Hornet. I've got a 1995 Browning catalog in front of me that lists all 3 of those. Browning may have made them in other calibers in following years, and Winchester has been selling the same (Miroku-made) gun in various calibers more recently (but not .243 as far as I know).
Bear in mind that the .45LC and other pistol-caliber versions (maybe 30-30 too)are the so-called "Traditional Hunter" version ... straight stock, non-gloss finish, crescent butt plate, iron sights. The .243 is the opposite (that is, pistol-grip stock, shiny finish, regular butt, no sights). I had a .223; nice gun, appreciably lighter and easier to handle than the 1885 HiWall or B-78. Traded it and, as usual, regret it.