[This space is intentionally left empty]
When a unit moves next to a unit with opfireYes, Minimum +8 to non proficient firepower with potential for +1 for marked op fire and +1 for spending a cp to raise non proficient fp (as kuhrusty said, some of those don't apply if the non proficient firepower is close to proficient firepower)
+4 for open ground
+3 for adjacent
+1 op fire
So it gets a +8 to FP ?
The -2 for final op fire may counter some of that though, but a +6 still isn't to be taken lightly.
In short, running up to an enemy is already a bad idea. Doing so in the open is worse. Sometimes it's necessary, but at least make sure the enemy is suppressed!