Weapon skills vs specific challenges

Cover, soft cover, isn't too good at stopping bullets, but it is great at deflecting them. This can present a challenge in a firefight. Sure, the counter or wall isn't going to stop the bullet, but it will deflect it enough to make it hart to hit the target behind. Yet with skill and training this can be overcome. A sniper can learn to fire through glass and sheets of metal, plywood, plastic, etc. compensating for the deviation of the bullet and still hitting the target.

Distance is another such challenge. The longer the flight of the bullet the more significant those small elements come into play. Once again skill and training come into play to overcome this challenge. Other elements I can enumerate are wind speed, air temperature and humidity.  All these come into play when making long shots.

What about close quarter combat? What comes into play there? How is skill applied when distance ensures a hit with today's modern weapons? I believe skill must be applied to reflex and the ability to respond quickly and faster in a dangerous situation, and in taking the best advantage of the environment by adding an insight the player may fail to grasp. An example of the former is a bonus to initiative while an example of the later is a bonus to cover.

Question is, at what point does the character's intuition overcome the player's decisions? Should the GM be a guiding hand or should the GM act with a strong arm? There's a broad spectrum when applying skill like this. Direct mechanical bonuses like skill to cover may make cover more effective. For example skill to use a brick wall to grant 90% cover while still being able to attack around/over it when lack of skill would only make such wall grant 70% effective cover.

Things get a bit trickier when the player decides to dash from cover to a new position and the character "feels" it's not so good an idea or has some "in game" feeling the idea isn't so good. In this way skill can be used to obtain some insight of the situation from the GM before making a decision, but it can also be used to change the decision in mid move. For example the player decides to dash forward, the character moves and just a split second later notices something, someone, aiming his way. The character dashes back to cover as the area is riddled with bullets.

Could be called the deja-vu dice? The dice are rolled once for the outcome to be, then "again" as modified by skill to alter the outcome. Thoughts? Could something like this be used in hand to hand combat to anticipate the move?

As I sit down to work with Weapons Free again I'm taking a closer look at skills and training.

• I like something more than simple bonuses to range and initiative.
• Skill must allow characters to have benefits in different situations and against different challenges.
• Skill, training and experience must enhance the whole unit, not only the individual member. 

Image source
http://media.dma.mil/2013/Dec/18/2000761117/600/400/0/131205-M-OM885-168.JPG
Lance Cpl. Lucas Corder, squad leader, Alpha Company, 1st Battalion, 7th Marine Regiment, and a native of Roseburg, Ore., directs Marines during live fire exercise on Range 210 at Marine Corps Air Ground Combat Center Twentynine Palms, Dec. 6, 2013. Staff Sgt. Jeremiah Bergeron, a platoon sergeant with Alpha Co., said Range 210 is probably one of the most dynamic ranges in the Marine Corps and it does an excellent job of mimicking a combat environment.