The recipe for military science (in both Factorio 0.17 and 0.18) is:
1 × piercing rounds magazine
1 × grenade
2 × wall
with crafting time of 10 s
outputs 2 × military science
The ratio for military science is very nice integer numbers:
10 × assembling machine for military science
1 × assembling machine for walls
8 × assembling machine for grenades
1 × assembling machine for firearm magazines
3 × assembling machine for piercing round magazines
Assuming you use assembling machines 1, this should produce 60 military science per minute.
At least as long as you have enough copper plates, iron plates, steel plates, stone bricks, and coal coming in.
And make sure you use enough fast inserters on the assembling machine for walls.
A total breakdown can be found, for example, with Kirk McDonald's Factorio Calculator:
https://kirkmcdonald.github.io/calc.htm ... -pack:f:10