To me a pin is a tactical position- not a result of a hit. Its the result of incoming fire. I am forced into a defensive posture because I am lucky enough not to be dead. I am pinned down when the enemy is suppressing me more than I am suppressing him. I am pinned when I see that the intersection ahead is being both suppressed and covered by multiple enemies. It makes me want to pause and think of a better plan. "Who has the K-Pulse or Mini Plas?"
However lets keep Pinned as a term we can use for a possible effect of being hit...
A wound on the other hand is non-fatal hit. Despite my armor, cover and sprint ability that damn gremlin rolled an 8.
The hit can have several effects:
"Earth Dogs DIE HARD" It can make a hero hole in my body and armor and piss me off. (No effect)
"Oh ****" I immediately stop, get small and seek cover I may find myself pinned or exposed with no cover. (Pin)
"I ain't got time to bleed" I can "ranger up" and continue the fight (-1move,-1fire)
"Medic!" It can take me out of action (incapacitated, but not dead for campaign)
"That didn't hurt"...thud (Kill)
Perhaps a less complicated rule to resolve the effect of a "exact hit"
The defender rolls a D6 using the target number of 6
+1 for expending a hero/leadership point (this forces them to use them wisely)
All other modifiers would really be irrelevant. They firer has already overcome range, cover, movement etc to actually score the hit. The defender has already taken account his armor etc.
Special Weapons like mention in the rule document could receive special modifiers
7+ Hero Hole
6 -5 Wound or Pin Defenders Choice
4 Wound or Pin (random)
3 Wound and Pin
1 Kill is scored
As always just brainstorming and having some fun. The scale could change. You could use 2D6 with additional options etc