Well, the weight gainer should help. Id avoid GNC though. There are Better online options and home recipes out there. I understand youre limited in the barracks, so the premade powders seem sensible.
Considering all of the running you guys do, you'll need to pull in
lots of cals to gain mass. Much, much More than the average 20 yr old.
I have news for you...The two best mass building exercises are Deadlifts and Squats. Both have major emphasis on wheels....and both will help increase your overall body mass. DONT sell yourself short on these. You will not reach your growth potential without them. I promise.
Other supps to consider: Fish oil, Multis (the gainer youre using has creatine but you should consider buying it in bulk online)
Pick up some olive oil or coconut oil. put 1-2 tbs into your shakes. Peanut butter is your friend by the way. Big cals = big gains.
Your routine, It sucks! A day dedicated to abs? lol come on. vanity and mass do not go hand in hand. Focus on bulking. You'll hit abs/core when you squat.
Shoulders/Bis
Chest/tris
Back/Legs
^ much more solid routine than what you proposed.
Now go eat something.

Preferably with LOTS of saturated fat in it.