[Stealhead]

Most likely Your Savage was designed for .223 and not 5.56mm.Most AR-15s and AR-15 based clones are chambered for 5.56mm.If the rifle was designed for 5.56mm you can use .223,5.56 M193 or what ever 5.56 that you want.If the rifle was designed for .223 you can't use 5.56mm in it.

If you ever plan on buying a AR at some point buy one that has been produced since the 1990s because they will use 5.56mm and then you can safely use both 5.56 and .223 in it.Your Savage and similar bolt action rifles where put on the market back in the 1970's and 80's when the AR-15 was no where near as common and as a result .223 and 5.56mm where in much lower demand.Now with so many newer ARs that can use both rounds people buy up both calibers like mad.

Even if you could safely chamber 5.56mm your rifle has a twist ratio that is not compatible with 5.56mm ammo especially anything based on the SS109 round and the bullet would tumble at some point in its flight.The Savage has a 1:10 or 1:12 ratio(it is likely stamped on the barrel some place) you should avoid any round that is above 62 grains but read your manual or ask a gunsmith or seller that knows what they are talking about it might be able to handle heaver rounds but the accuracy will be lowered because it is a varmint gun optimized for 30-55gr rounds that is good because those are cheaper than heavier rounds.

ARs have a lower twist ratio so they can better accommodate differing rounds.that being said many people will have more than barrel and upper.They will have a varmint upper with a .223 chamber and a rifle with a 1:10 or so ratio and have a another upper and barrel optimized for the newer heavy grain 5.56 rounds.

I have an upper and barrel that accepts .468 SOCOM it is a boar killer.The nice thing is that .468 rounds fit just fine inside any magazine designed for 5.56mm.

Have fun with that Savage but save at least some of your money to buy some more rifles of your own.