Originally Posted by ams556
I'd like to build one as well.
I wonder if there are any feeding issues.
Not with the right upper.
Costs for the 5.45mm round are still between 15 and 19 cents and often they get delivered in spam cans perfect for decades long storage...
There are ways to convert USGI mags but the most reliable magazine solutions are purpose built 5.45mm mags.
This was going to be my strategy to stack ammo deep but i could never find a local range that would let me shoot so
I sold my adams arms upper a couple of cases of Ammo and eight 5.45mm mags.