Assuming he's getting a new action and dies already, with lots of powders at $600/8lbs, you're recovering the cost of new mags and a cartridge holder pretty quick shooting max 25gr of powder vs 40ish... Nevermind that brass is cheap and plentiful.The downside of 223 is the weird, atypical boltface and cartridge shape. Now you need a special bolt, special magazines, special cartridge holder for reloading equipment... Easier to just go with a 308-based .22cal (22 creed, 22 BR, 22 BRA, 22 dasher...).