We get questions here from several nations, and all US states- so we can't give you a meaningful answer- since we don't know where you are! Sorry-
100-400 or so
AR15, M16, M4, Ruger Mini 14
100-460 USD or so
100-460 or so
The Ruger Mini-14 Ranch Rifle marked as .223 can safely fire the .223 AND the 5.56 NATO military cartridge. The Ruger Mini-14 TARGET model should only fire .223 ammo- no 5.56 mm
250-425 USD
100-435 USD
Depends. If you mean the Ruger Mini-14 or Ranch Rifle, yes, you can. It is chambered for .223 and 5.56x45 ammo. If you read the owner's manual (available on the Ruger website) it will tell you that on page 13. The Target Model is ONLY for .223. Of course, the 6.8mm and the Mini-30 use different ammo entirely.
$300 IF CLEAN
The Ruger Web site says the Mini-14 Ranch Rifle and the Mini-14 Tactical Rifle, can be used with either the .223 or 5.56mm round: Mini-14 Target Rifles ONLY accept .223 Rem. ammunition. 5.56 NATO cannot be used in this model. Probably due to tighter chambering dimensions for accuracy.
100-500 or so
Yes, it was. Go to the Ruger website for more information. The military round is the 5.56x45 - while dimensionally similar to the .223 Remington, it is not entirely the same. The standard and Ranch models of the Mini 14 have a 5.56x45 chamber, which can accept both 5.56 and .223 Remington ammo. The Target models, however, have a dedicated .223 Remington chamber, and were not designed to use 5.56x45 military ammo.