I've been thinking about a 5.45x39 build due to the price difference in ammo. I know the surplus stuff is corrosive, but I'm not afraid to use it. I've cleaned many of old Mausers after shooting the corrosive 8mm stuff. I already have a spare lower and upper available. I've priced it out and for about $750, I can have a badass rifle. I've videos to modify Pmags to hold 28 rounds of the 5.45x39 and that still work for the 5.56 so I can use my regular mags. And with spam cans of 5.45x39 selling for $170/1080 rnds, it's hard to argue the cost savings. What I'd really like to do is have about 2 spam cans of surplus handy at all times. Then I'd have the 5.45x39 as a SHTF gun. Just keep it in a carry case full of mags and ready to roll if needed. Anyone else do a 5.45x39 build? Am I crazy? Should I just spend the $750 on more 223 ammo?