What diameter of bullets does the 5.45x39mm round shoot?  Does it shoot the normal .224 diameter bullet that the majority of the other .22cal centerfires shoot?

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so, how would one reload for a 5.45?  I haven't seen any component bullets in that size.

Reloading the 5.45 is extremely non practical at this time.  You could swage 5.56 down to 5.45, but getting brass is next to impossible at this time.  Considering how cheap 5.45 is right now, and unless you were smart enough to buy one of those East German 5.45 bolt action sniper rifles (SSG 82) out of SGN about 6 years ago, reloading 5.45 would be a big waste of time and money.  The most readily available 5.45 platforms are not capable of producing accuracy that justifies handloaded ammo.

Here is a SSG 82