It isn't mandatory to reduce or remachine the AK (or SKS) bolt face for the smaller cartridge. They will feed wth the larger diameter bolt face however... the extractor must be modified to grab the smaller round and also push the rim accross the bolt face upon extraction so the stock ejector can hit it. It works !!
The modified extactor has an altered (deeper) slot in the bolt to allow a bit more movement. I have seen this in conversions from 7.62x39mm to .223 cal ammo. This clone extractor and bolt thing saves shopping for a .223 bolt (and carrier etc...).
The trick extractor was made by grinding and reshaping the the original, no heating or forging was needed. The bolt was modified using the ever-popular Dremel tool !!!