Using ak74 mags mean you would lose your bolt lock and they already have a 223 so I see no need plus I have never even seen bulk 5.45 in canada ive never even seen a box outside a gun show . Having a 7.62x51 means we would have a 308 pistol grip battle rifle for around $1500 thats 1000 less than anything else on the market id buy 1 in a second.