I'm kinda banking on the hitbox system to help with this: while it's very resilient to most forms of damage you can down it in one shot with any explosive to the engines or the tail rotor. The Blast/Anti-Material rifles are also designed to do heavy vehicle damage - the blast rifle will take down almost any vehicle with 2-3 shots to it's engine or other critical components, and the HAT rockets will kill everything in one hit except for armor hitboxes on tanks. Taking down a vehicle can be very doable if you know how to do it and have the skill to land the shots, and conversely, skilled pilots can protect their vehicle with good situational awareness and positioning. I also
made a spreadsheet with all the values for planned vehicles and weapons because I have autism.
Vehicles are weird to balance because the whole idea behind something like a tank is that it's very hard for infantry to actually destroy a tank, but tanks also have to output enough damage to destroy other tanks, so you end up with very hard to kill vehicles fighting other very hard to kill vehicles and all the ground troops caught in the crossfire just getting grinded. This is the packs most problematic theme, because at the end of the day in order for these low TTK firefights to work out, you need distance, which means a lot of space in your maps. This doesn't play well with Blockland's dwindling player-count. But it does make for a lot of chaotic fun on unconventional servers like Tito's.
The 30mm does have more bark than bite though. The lethal radius is around 8 bricks, I will adjust the explosion to represent this better. I really am a sucker for big damage output though. It does suck getting pwn'd by mega death fail tanks but blowing stuff to pieces in an attack helicopter makes up for it