That is a loaded question amigo! Factory barrels for the 30-30 are often highly praised or cursed and alot has to do with the age of the barrel and how you load for it. Almost all of the vintages of the barrels will typically shoot 2-3 inch groups with factory ammo if you can sight it and hold it right. Usually a 4x or better scope will really help with group sizes at 100 yards.
Some of the vintages of the barrels are throated that make it difficult to get any more accurate than that, but that is only the ones that really have little or no throat and that is easy to fix! I have a ten inch bull that was one of those 2-3 inch barrels, I had a gunsmith throat it with a throating reamer to accept the bullets that I had planned on using and the barrel immediately became a sub-one inch gun. The throating job cost less than $25 and was worth a million. I also had my super 16 carbine barrel similarly throated and it also is a sub one inch gun.
Even in a ten inch, the 30-30 is fun and a good hunting barrel, and ammo is cheap and plentiful if you don't reload. The recoil out of the 14 inch barrels isn't bad at all, the 10 barks a little louder, but still isn't bad...much less than hot loaded 44s!
Good luck with your barrel, hopefully it will shoot just like you want without any touch up, but if it needs the touch up, fear not, it is an easy job.
regards,
graycg