Before anyone learns this, ask who will carry it. The HMLMG takes a rifle body just like the AK and the bolt, and in a group that holds a compound or a roof through online raids, that body earns more here than in a fourth AK. In a group that roams, it doesn't.
The part that catches people out is the gears. The calculator counts them as is because most come out of the recycler, from broken gates, doors and electrical junk. Crafting your own means another blueprint and a pile of scrap at the Level 3 bench, and an armored door wants them in fives. Keep one gear box and decide which upgrade it pays for.
A looted M249 does the same job with no blueprint, but you can't replace it. The HMLMG is the one you rebuild after a lost defence, so queue a big batch of 5.56 with it: a belt-fed gun empties a box fast.
Questions
HMLMG ×10: how many resources?
High Quality Metal ×300, Gears ×20, Metal Spring ×30, Rifle Body ×10.