Will your 223 5.56 shoot 62 grain bullets accurate at 600 yrds the rifeling twist is 1in9 How heavy of a grain can i use with out wearing the crome lined barrel?

1 in 9 is actually the ideal pitch for the 5.56x45 SS109/M855 cartridge. The reason the military went with 1 in 7 is because it could fire 62 grain ball ammo and 64 grain tracer ammo to matching flight characteristics. You're perfectly fine with the barrel you have.

As for the chrome lining, that all depends, and I personally advise most civilian shooters not to bother with it. Several companies offer chrome lined barrels, but most of them don't line their barrels to the actual military specifications (in spite of their claims of being mil spec). This often results in the chrome lining being substandard, eventually flaking off, and causing a reduction in accuracy. You should also note that non-chrome lined barrels are typically more accurate than chrome lined barrels, because of imperfections created by the chrome lining process.

Some manufacturers of cartridges up to 75 grain actually recommend a 1 in 9 pitch. It will not, however, properly stabilise the 77 grain cartridges, nor the 80 grain .223 Wylde cartridges (which require a specific chamber, anyhow).

Also note that, while .223 Remington and 5.56x45 are dimensionally similar, they are not one in the same.