First of all, make the guns visible (I cant see them past 300-400 yards).
Frankly, I do not understand the obsesion of some players with mannable guns. Cant you just pick up a flak/M16 or a plane? Do we really need manned guns that can erase all the enemy planes within 3-4 miles range? I'm pretty sure that timed or not timed, most manned 88 kills would be just direct hits.
People in planes or GVs spend 5 or 10 minutes to reach a base and as they aproach, a player, spending just 2 seconds, jumps behind his safe big gun and vaporize the enemy 3 miles away.