A Savage 12 in 223 is a very precise/accurate rifle. I've had an older-Pre Accutrigger Model 12 for many years,it's one of the most accurate rifles that I've ever owned.
The smallest 5 shot group that I've ever shot with it was .168",at 100 yards,and that was with 60gr VMax handloads.
If you don't handload,your groups will be only as good as the ammo that is used,and how well the particular gun likes to shoot that ammo. You will also need to get the correct barrel twist for whatever bullet weights you want to shoot.
A 1-12 twist is for lighter weight bullets,a 1-9 is a good general purpose,it will shoot up to 75gr bullets.A 1-7 twist will shoot the heavier bullets,but these twist rates are mainly used by people that handload,there's not too many choices of factory loads for the 75gr and up match bullets.
I prefer to use a 1-8 or 1-9 twist with a 223 caliber.
There are several great brands of rifles out there. Just make sure what the barrel twist is on the rifle before you buy one,then you'll know what type of ammo that it will shoot before you find out you got the wrong twist rate.