Our game is ever so loosely based on reality.
And just to make a point. An average 9mm bullet travels at about 300 meters/second. A gun in our game that travels at around that speed is the Heavy Flak at 240m/s. Another is the Gatling at 300m/s. Most of are guns travel quite a bit faster. .50 caliber sniper rifles are at about 800m/s. The Field Gun was at 1200m/s and is now at 750m/s. However, at the end of the day none of that crap matters because you're flying around in a virtual environment. Reality is simulated and the way we perceive simulation is very different from how we perceive reality.
To put it simply, we are not a simulation. The changes to the Field Gun can be compared to making it like it has the speed of a 9mm compared to before, fine, but I don't care. It's about how it feels and how it affects gameplay. I have that freedom to shape gameplay in certain ways because we are only loosely based on reality. It's a good freedom to have because simulations are heavily constrained and imbalances are hard to fix.