In the mid-fifties, 6mm wildcat cartridges 
were experiencing increasing interest, and in 
1955 Winchester responded in kind with the .243 
Winchester.  Formed by neck-sizing the successful 
.308 WInchester to .243 inches, it was instantly 
popular in Winchester's intended multi-purpose 
role, spanning varmints to deer-sized game.  
Other manufacturers followed suit with their own 
6mm rounds, but none were to reach the 
"everyone-knows-it" familiarity that the .243 
Winchester would attain.

    Particularly well-suited to the Winchester 
Model 88 Lever-Action, the cartridge was adapted 
to the long-lived Savage 99 line also.  Of 
course, it is a popular chambering in 
short-action bolt-actions.

    Factory ammunition sports an 80-grain 
jacketed bullet at 3350 fps.  The .243 has long 
been appreciated as a flat-shooting cartridge 
quite suitable for long-range varmint work.