Here's a little guide for the "Iron Fist" achievement I found online.
Iron Fist (15g)
Destroy all towers and bunkers in 'Blood and Iron'. (Solo or co-op)
part 1 where you have to destroy the 88's
bunker 1 & 2: cant miss them at the end of the big field.
tower 1: left side of the field near the third 88 cannon
tower 2: in front of the 2 bunkers
tower 3: right side of the field
tower 4: Behind the right bunker
Part 2 where you have to destroy the radio tower
bunker 3: as soon as you can see the radio tower there is a overturned truck on your left the bunker is behind it a bit hidden in the woods.
tower 5: in front of the radio tower
tower 6: behind the radio tower
Part 3 the big bunker
bunker 4: big bunker cant miss it but make sure you destroy both sides.
tower 7: to the east of the big bunker
tower 8: behind the big bunker
part 4 train station
tower 9 & 10: cant miss them you will see them as soon as you reach the ledge.
tower 11 & 12 & 13: to your left, right and one in front of you before you drive into the train station.
*there are "legs" for another tower but that one was already destroyed not by me.
Achievement unlockes after you shoot the last tower. If you missed something you can go back.