Now that everyone's here, here's the weapons I think John should use in the future.
.950 JDJThis is a gun I wanted John to get in the future.
This is THE ULTIMATE armor piercing weapon!!!
The gun is not that much different from a 20 mm rifle, other than the fact that it has a higher amount of force behind the bullet and a fatter round, making it more damaging to what it hits.
I was thinking that it could be a militarized version of the gun, or even custom made. Maybe something like a larger Barret sniper. The
Barret .950 JDJ.
John would be able to handle it, due to his weight and strength, and god help you if he melees you with it.:p
Punt GunA guy can dream, can't he?
The punt gun uses 2-gauge shells and is F*CKING HUGE!!!
John would be okay for the most part, but he would definitely be affected by the recoil.
XM25
These are the types of ammunition it uses.

It is basically a smart grenade launcher. John would carry High-Explosive and Armor Piercing 25 mm shells, maybe door-breaching.
AA-12A shotgun to John's arsenal. John would use 12 Gauge and Frag-12 rounds.