You will have to define further. Ever made? Rifle or handgun? Bolt, semi, single shot, revolver, pistol?
22-250, 220 Swift, 243, 6mm Rem, 25-06, 308. Other versions of the 77 were in MANY other calibers.
Ruger American Rifle short action calibers (.243 Win, .308 Win, 7mm .08 Rem, 22-250)
Two different calibers, two different slides, do not mix and match.
3 different calibers
saints row 3
A TRUE 12mm cartridge would be the .480 Ruger, or .475 Linebaugh. However, I have seen both the .45 ACP and the .50 Browning called 12mm (they are 11.45mm and 12.7mm)
If you are referring to a Sturm & Ruger Co. Mini-14, then the answer is that most were manufactured in .223 Remington. The Ruger factory has from time to time released the Mini-14 rifle in .222 Remington in limited numbers, most likely to satisfy limited markets (some countries do not allow sales of "military" calibers.)
The Fisherman
Dozens of calibers from .22 up through major hunting calibers.
Puzzle piece guy.
Nope.
it is 1: planB 2: birdhouse 3:darkstar